Ошибки при изменении количества кнопок на форме.

function[]=forma()
global  f scrsz n
scrsz = get(0,'ScreenSize');
f=figure('Position',[1 scrsz(2) scrsz(3) scrsz(4)],'NumberTitle','off','name','Forma');
n=uicontrol(f,'Style','edit','position',[100 1 100 50]);
uicontrol(f,'Style','pushbutton', 'String', 'Button','position',[1 1 100 50],'callback','knopka')
end

function[]=knopka()
global f n e m q s 
r=get(n,'string');
scr = get(0,'ScreenSize');
k=50;
q=str2num(r);
e=7;
 
if q>e 
  q=e;
end
s=uicontrol(f,'Style', 'slider','Position', [220 50 235 16],'Min', 1, 'Max', q,'SliderStep', [1/(q-1) 1/q],'value',1,'callback','slider');
for i=1:q;
m(i)=uicontrol(f,'Style','pushbutton', 'String', 'Button','position',[1 k 100 50]);
k=k+60;
end
 
for j=1:q;
m(j)=uicontrol(f,'Style','pushbutton', 'String', 'Button','position',[k  100 100 50]);
k=k+100;
end

function[]=slider()
global s q m
g =get(s,'value');
%set(n, 'String', g);
for j=1:q
 set( m(j),'enable','on');   
end
set(m(ceil(g)),'enable','off');
end