Ошибка при построении графической формочки для голосования

<?php
$vote = $_REQUEST['vote'];
if(!$db_conn=new mysqli('localost', 'poll', 'poll', 'pool')){
    echo"Нельзя подключится к базе";
exit;   
}
if(!empty($vote)){
$vote=addslashes($vote);
$query="update poll_results set num_votes=num_votes + 1 where candidate='$vote'";
}
if(!($result=$db_conn->query($query))){
    echo "Неполучилось связать запрос с базой";
    exit;
}
$query='select * from poll_results';
if(!($result=$db_conn->query($query))) {
    echo"Неполучилось вывести с базы данные";
    exit;
}
$num_candidates = $result->num_rows;
$total_votes=0;
while($row = $result->fetch_object()){
    $total_votes += $row->num_votes;
}
$result->data_seek(0);
$width = 500;
$left_margin = 50;
$right_margin = 50;
$bar_height = 40;
$bar_spacing = $bar_height/2;
$font = 'arial';
$title_size = 16;
$main_siz = 12;
$small_size = 12;
$text_indent = 10;
$x = $left_margin + 60;
$y = 50;
$bar_unit=($width-($x + $right_margin)) / 100;
$height = $num_candidates * ($bar_height + $bar_spacing)+50;
$im =ImageCreateTrueColor($width, $height);
$white=ImageColorAllocate($im, 255, 255, 255);
$blue=ImageColorAllocate($im, 0, 64, 128);
$black=ImageColorAllocate($im, 0, 0, 0);
$pink = ImageColorAllocate($im,255,78,243);
$text_color = $black;
$percent_color = $black;
$bg_color = $white;
$line_color = $black;
$bar_color = $blue;
$number_color = $pink;
ImageFilledRectangle($im, 0, 0, $width, $height, $bg_color);
ImageRectangle($im, 0, 0, $width-1, $height-1, $line_color);
$title = 'Результаты опроса';
$title_dimensions = ImageTTFBBox($title_size, 0, $font, $title);
$title_length = $title_dimensions[2] - $title_dimensions[0];
$title_height = abs($title_dimensions[7] - $title_dimensions[1]);
$title_above_line = abs($title_dimensions[7]);
$title_x = ($width-$title_length) / 2 ;
$title_y = ($y - $title_height)/ 2 + $title_above_line;
ImageTTFText($im, $title_size, 0, $title_x, $title_y, $text_color, $font, $title);
ImageLine($im, $x, $y - 5, $x, $height - 15, $line_color);
while ($row = $result->fetch_object()) {
    if ($total_votes > 0){
        $percent = intval(($row->num_votes / $total_votes)*100);
    }   else{
    $percent = 0;}
    $percent_dimensions = ImageTTFBBox($main_size, 0, $font, $percent.'%');
    $percent_length=$percent_dimensions[2] - $percent_dimensions[0];
    ImageTTFText ($im, $main_size, 0, $width-$percent_length-$text_indent,
    $y+($bar_height/2), $percent_color, $font, $percent.'%');
    $bar_length = $x + ($percent * $bar_unit);
    ImageFilledRectangle($im, $x, $y-2, $bar_length, $y + $bar_height, $bar_color);
    ImageTTFText($im, $main_size, 0, $text_indent, $y + ($bar_height/2),
    $text_color, $font, "$row->candidate");
    ImageRectangle($im, $bar_length + 1, $y-2,
    ($x + (100 * $bar_unit)), $y + $bar_height, $line_color);
    ImageTTFText($im,$small_size, 0, $x + (100 * $bar_unit)- 50, $y + ($bar_height / 2),
    $number_color, $font, $row->num_votes.'/'.$total_votes);
    $y = $y + ($bar_height + $bar_spacing);
    Header('Content-type : image/png');
    ImagePNG($im);
    ImageDestroy ($im);?>