Не работают два JS скрипта на одной странице

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>
 
<script>
$(document).ready(function(){
    $("#back-top").hide();
    $(function () {
        $(window).scroll(function () {
            if ($(this).scrollTop() > 100) {
                $('#back-top').fadeIn();
            } else {
                $('#back-top').fadeOut();
            }
        });
        $('#back-top a').click(function () {
            $('body,html').animate({
                scrollTop: 0
            }, 800);
            return false;
        });
    });
 
});
</script>

LightboxOptions = Object.extend({
    fileLoadingImage:        'images/loading.gif',     
    fileBottomNavCloseImage: 'images/closelabel.gif',
 
    overlayOpacity: 0.8,   
    animate: true,       
    resizeSpeed: 7,  
    and 10=fastest)
 
    borderSize: 10,   
    labelImage: "Изображение",
    labelOf: "из"
}, window.LightboxOptions || {});
var Lightbox = Class.create();
 
Lightbox.prototype = {
    imageArray: [],
    activeImage: undefined,
    
    initialize: function() {    
        
        this.updateImageList();
        
        this.keyboardAction = this.keyboardAction.bindAsEventListener(this);
 
        if (LightboxOptions.resizeSpeed > 10) LightboxOptions.resizeSpeed = 10;
        if (LightboxOptions.resizeSpeed < 1)  LightboxOptions.resizeSpeed = 1;
 
        this.resizeDuration = LightboxOptions.animate ? ((11 - LightboxOptions.resizeSpeed) * 0.15) : 0;
        this.overlayDuration = LightboxOptions.animate ? 0.2 : 0;  // shadow fade in/out 
        var size = (LightboxOptions.animate ? 250 : 1) + 'px';
        
 
        var objBody = $$('body')[0];
 
        objBody.appendChild(Builder.node('div',{id:'overlay'}));
    
        objBody.appendChild(Builder.node('div',{id:'lightbox'}, [
            Builder.node('div',{id:'outerImageContainer'}, 
                Builder.node('div',{id:'imageContainer'}, [
                    Builder.node('img',{id:'lightboxImage'}), 
                    Builder.node('div',{id:'hoverNav'}, [
                        Builder.node('a',{id:'prevLink', href: '#' }),
                        Builder.node('a',{id:'nextLink', href: '#' })
                    ]),
                    Builder.node('div',{id:'loading'}, 
                        Builder.node('a',{id:'loadingLink', href: '#' }, 
                            Builder.node('img', {src: LightboxOptions.fileLoadingImage})
                        )
                    )
                ])
            ),
            Builder.node('div', {id:'imageDataContainer'},
                Builder.node('div',{id:'imageData'}, [
                    Builder.node('div',{id:'imageDetails'}, [
                        Builder.node('span',{id:'caption'}),
                        Builder.node('span',{id:'numberDisplay'})
                    ]),
                    Builder.node('div',{id:'bottomNav'},
                        Builder.node('a',{id:'bottomNavClose', href: '#' },
                            Builder.node('img', { src: LightboxOptions.fileBottomNavCloseImage })
                        )
                    )
                ])
            )
        ]));
 
 
        $('overlay').hide().observe('click', (function() { this.end(); }).bind(this));
        $('lightbox').hide().observe('click', (function(event) { if (event.element().id == 'lightbox') this.end(); }).bind(this));
        $('outerImageContainer').setStyle({ width: size, height: size });
        $('prevLink').observe('click', (function(event) { event.stop(); this.changeImage(this.activeImage - 1); }).bindAsEventListener(this));
        $('nextLink').observe('click', (function(event) { event.stop(); this.changeImage(this.activeImage + 1); }).bindAsEventListener(this));
        $('loadingLink').observe('click', (function(event) { event.stop(); this.end(); }).bind(this));
        $('bottomNavClose').observe('click', (function(event) { event.stop(); this.end(); }).bind(this));
 
        var th = this;
        (function(){
            var ids = 
                'overlay lightbox outerImageContainer imageContainer lightboxImage hoverNav prevLink nextLink loading loadingLink ' + 
                'imageDataContainer imageData imageDetails caption numberDisplay bottomNav bottomNavClose';   
            $w(ids).each(function(id){ th[id] = $(id); });
        }).defer();
    },
 
    updateImageList: function() {   
        this.updateImageList = Prototype.emptyFunction;
 
        document.observe('click', (function(event){
            var target = event.findElement('a[rel^=lightbox]') || event.findElement('area[rel^=lightbox]');
            if (target) {
                event.stop();
                this.start(target);
            }
        }).bind(this));
    },
    
    start: function(imageLink) {    
 
        $$('select', 'object', 'embed').each(function(node){ node.style.visibility = 'hidden' });
 
        // stretch overlay to fill page and fade in
        var arrayPageSize = this.getPageSize();
        $('overlay').setStyle({ width: arrayPageSize[0] + 'px', height: arrayPageSize[1] + 'px' });
 
        new Effect.Appear(this.overlay, { duration: this.overlayDuration, from: 0.0, to: LightboxOptions.overlayOpacity });
 
        this.imageArray = [];
        var imageNum = 0;       
 
        if ((imageLink.rel == 'lightbox')){
            // if image is NOT part of a set, add single image to imageArray
            this.imageArray.push([imageLink.href, imageLink.title]);         
        } else {
            // if image is part of a set..
            this.imageArray = 
                $$(imageLink.tagName + '[href][rel="' + imageLink.rel + '"]').
                collect(function(anchor){ return [anchor.href, anchor.title]; }).
                uniq();
            
            while (this.imageArray[imageNum][0] != imageLink.href) { imageNum++; }
        }
 
        // calculate top and left offset for the lightbox 
        var arrayPageScroll = document.viewport.getScrollOffsets();
        var lightboxTop = arrayPageScroll[1] + (document.viewport.getHeight() / 10);
        var lightboxLeft = arrayPageScroll[0];
        this.lightbox.setStyle({ top: lightboxTop + 'px', left: lightboxLeft + 'px' }).show();
        
        this.changeImage(imageNum);
    },
 
    changeImage: function(imageNum) {   
        
        this.activeImage = imageNum; // update global var
 
        // hide elements during transition
        if (LightboxOptions.animate) this.loading.show();
        this.lightboxImage.hide();
        this.hoverNav.hide();
        this.prevLink.hide();
        this.nextLink.hide();
        // HACK: Opera9 does not currently support scriptaculous opacity and appear fx
        this.imageDataContainer.setStyle({opacity: .0001});
        this.numberDisplay.hide();      
        
        var imgPreloader = new Image();
        
        // once image is preloaded, resize image container
 
 
        imgPreloader.onload = (function(){
            this.lightboxImage.src = this.imageArray[this.activeImage][0];
            this.resizeImageContainer(imgPreloader.width, imgPreloader.height);
        }).bind(this);
        imgPreloader.src = this.imageArray[this.activeImage][0];
    },
 
    resizeImageContainer: function(imgWidth, imgHeight) {
 
        // get current width and height
        var widthCurrent  = this.outerImageContainer.getWidth();
        var heightCurrent = this.outerImageContainer.getHeight();
 
        // get new width and height
        var widthNew  = (imgWidth  + LightboxOptions.borderSize * 2);
        var heightNew = (imgHeight + LightboxOptions.borderSize * 2);
 
        // scalars based on change from old to new
        var xScale = (widthNew  / widthCurrent)  * 100;
        var yScale = (heightNew / heightCurrent) * 100;
 
        // calculate size difference between new and old image, and resize if necessary
        var wDiff = widthCurrent - widthNew;
        var hDiff = heightCurrent - heightNew;
 
        if (hDiff != 0) new Effect.Scale(this.outerImageContainer, yScale, {scaleX: false, duration: this.resizeDuration, queue: 'front'}); 
        if (wDiff != 0) new Effect.Scale(this.outerImageContainer, xScale, {scaleY: false, duration: this.resizeDuration, delay: this.resizeDuration}); 
 
        // if new and old image are same size and no scaling transition is necessary, 
        // do a quick pause to prevent image flicker.
        var timeout = 0;
        if ((hDiff == 0) && (wDiff == 0)){
            timeout = 100;
            if (Prototype.Browser.IE) timeout = 250;   
        }
 
        (function(){
            this.prevLink.setStyle({ height: imgHeight + 'px' });
            this.nextLink.setStyle({ height: imgHeight + 'px' });
            this.imageDataContainer.setStyle({ width: widthNew + 'px' });
 
            this.showImage();
        }).bind(this).delay(timeout / 1000);
    },
   
    showImage: function(){
        this.loading.hide();
        new Effect.Appear(this.lightboxImage, { 
            duration: this.resizeDuration, 
            queue: 'end', 
            afterFinish: (function(){ this.updateDetails(); }).bind(this) 
        });
        this.preloadNeighborImages();
    },
 
    updateDetails: function() {
    
        // if caption is not null
        if (this.imageArray[this.activeImage][1] != ""){
            this.caption.update(this.imageArray[this.activeImage][1]).show();
        }
        
        // if image is part of set display 'Image x of x' 
        if (this.imageArray.length > 1){
            this.numberDisplay.update( LightboxOptions.labelImage + ' ' + (this.activeImage + 1) + ' ' + LightboxOptions.labelOf + '  ' + this.imageArray.length).show();
        }
 
        new Effect.Parallel(
            [ 
                new Effect.SlideDown(this.imageDataContainer, { sync: true, duration: this.resizeDuration, from: 0.0, to: 1.0 }), 
                new Effect.Appear(this.imageDataContainer, { sync: true, duration: this.resizeDuration }) 
            ], 
            { 
                duration: this.resizeDuration, 
                afterFinish: (function() {
                    // update overlay size and update nav
                    var arrayPageSize = this.getPageSize();
                    this.overlay.setStyle({ height: arrayPageSize[1] + 'px' });
                    this.updateNav();
                }).bind(this)
            } 
        );
    },
 
    updateNav: function() {
 
        this.hoverNav.show();               
if (this.activeImage > 0) this.prevLink.show();
 
        if (this.activeImage < (this.imageArray.length - 1)) this.nextLink.show();
        
        this.enableKeyboardNav();
    },
 
 
    enableKeyboardNav: function() {
        document.observe('keydown', this.keyboardAction); 
    },
 
  
    disableKeyboardNav: function() {
        document.stopObserving('keydown', this.keyboardAction); 
    },
 
    keyboardAction: function(event) {
        var keycode = event.keyCode;
 
        var escapeKey;
        if (event.DOM_VK_ESCAPE) {  // mozilla
            escapeKey = event.DOM_VK_ESCAPE;
        } else { // ie
            escapeKey = 27;
        }
 
        var key = String.fromCharCode(keycode).toLowerCase();
        
        if (key.match(/x|o|c/) || (keycode == escapeKey)){ // close lightbox
            this.end();
        } else if ((key == 'p') || (keycode == 37)){ // display previous image
            if (this.activeImage != 0){
                this.disableKeyboardNav();
                this.changeImage(this.activeImage - 1);
            }
        } else if ((key == 'n') || (keycode == 39)){ // display next image
            if (this.activeImage != (this.imageArray.length - 1)){
                this.disableKeyboardNav();
                this.changeImage(this.activeImage + 1);
            }
        }
    },
 
    preloadNeighborImages: function(){
        var preloadNextImage, preloadPrevImage;
        if (this.imageArray.length > this.activeImage + 1){
            preloadNextImage = new Image();
            preloadNextImage.src = this.imageArray[this.activeImage + 1][0];
        }
        if (this.activeImage > 0){
            preloadPrevImage = new Image();
            preloadPrevImage.src = this.imageArray[this.activeImage - 1][0];
        }
    
    },
 
   
    end: function() {
        this.disableKeyboardNav();
        this.lightbox.hide();
        new Effect.Fade(this.overlay, { duration: this.overlayDuration });
        $$('select', 'object', 'embed').each(function(node){ node.style.visibility = 'visible' });
    },
 
    getPageSize: function() {
            
         var xScroll, yScroll;
        
        if (window.innerHeight && window.scrollMaxY) {  
            xScroll = window.innerWidth + window.scrollMaxX;
            yScroll = window.innerHeight + window.scrollMaxY;
        } else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
            xScroll = document.body.scrollWidth;
            yScroll = document.body.scrollHeight;
        } else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
            xScroll = document.body.offsetWidth;
            yScroll = document.body.offsetHeight;
        }
        
        var windowWidth, windowHeight;
        
        if (self.innerHeight) { // all except Explorer
            if(document.documentElement.clientWidth){
                windowWidth = document.documentElement.clientWidth; 
            } else {
                windowWidth = self.innerWidth;
            }
            windowHeight = self.innerHeight;
        } else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
            windowWidth = document.documentElement.clientWidth;
            windowHeight = document.documentElement.clientHeight;
        } else if (document.body) { // other Explorers
            windowWidth = document.body.clientWidth;
            windowHeight = document.body.clientHeight;
        }   
        
        // for small pages with total height less then height of the viewport
        if(yScroll < windowHeight){
            pageHeight = windowHeight;
        } else { 
            pageHeight = yScroll;
        }
    
        // for small pages with total width less then width of the viewport
        if(xScroll < windowWidth){  
            pageWidth = xScroll;        
        } else {
            pageWidth = windowWidth;
        }
 
        return [pageWidth,pageHeight];
    }
}
 
document.observe('dom:loaded', function () { new Lightbox(); });