hiding a lot of buttons doesn't work after 40 buttons

hi every one

i create a game with as3,it has a lot of questions of multi choose,so i have a lot of buttuns that i hide them all at the beginning of the game ex ( a10.visible=false;

b10.visible=false;...... etc )

the proplem is :when i start to create the eleven question with hte same code of hiding it doesn't work.

why?

my code for the first question is:

import flash.display.MovieClip;
import flash.events.MouseEvent;

btn.addEventListener(MouseEvent.CLICK,clickhandler);
function clickhandler(event:MouseEvent):void {
var num1 =Math.round((Math.random()*5) + 1);
rno.text = String(num1);

}

var q1:MovieClip = q1
q1.visible=false;
a1.visible=false;
b1.visible=false;
c1.visible=false;
d1.visible=false;
var q7:MovieClip = q7
q7.visible=false;
a7.visible=false;
b7.visible=false;
c7.visible=false;
d7.visible=false
var q2:MovieClip = q2
q2.visible=false;
a2.visible=false;
b2.visible=false;
c2.visible=false;
d2.visible=false;
var q3:MovieClip = q3
q3.visible=false;
a3.visible=false;
b3.visible=false;
c3.visible=false;
d3.visible=false;
var q4:MovieClip = q4
q4.visible=false;
a4.visible=false;
b4.visible=false;
c4.visible=false;
d4.visible=false;
var q5:MovieClip = q5
q5.visible=false;
a5.visible=false;
b5.visible=false;
c5.visible=false;
d5.visible=false;
var q8:MovieClip = q8
q8.visible=false;
a8.visible=false;
b8.visible=false;
c8.visible=false;
d8.visible=false;
var q9:MovieClip = q9
q9.visible=false;
a9.visible=false;
b9.visible=false;
c9.visible=false;
d9.visible=false;
var q10:MovieClip = q10
q10.visible=false;
a10.visible=false;
b10.visible=false;
c10.visible=false;
d10.visible=false;

// the next who doesn't woek //
var q11:MovieClip = q11
q11.visible=false;
a11.visible=false;

b11.visible=false;
c11.visible=false;
d11.visible=false;

// the rest of the code //

ball1. buttonMode = true;
ball1.addEventListener(MouseEvent.MOUSE_DOWN, fl_ClickToDrag);

function fl_ClickToDrag(event:MouseEvent):void
{
ball1.startDrag();
addChild (ball1)
}

ball2.addEventListener(MouseEvent.MOUSE_DOWN, fl_ClickToDrag2);

function fl_ClickToDrag2(event:MouseEvent):void
{
ball2.startDrag();
addChild (ball2)
}

stage.addEventListener(MouseEvent.MOUSE_UP, fl_ReleaseToDrop);

function fl_ReleaseToDrop(event:MouseEvent):void
{
ball1.stopDrag();

if (ball1. hitTestObject (s1))
{
q1.visible=true;
a1.visible=true;
b1.visible=true;
c1.visible=true;
d1.visible=true;

}

b1.addEventListener(MouseEvent.CLICK,clickhandler4);
function clickhandler4(event:MouseEvent):void{

q1.visible=false;
a1.visible=false;
b1.visible=false;
c1.visible=false;
d1.visible=false;
if(stage.contains(b1))
removeChild(b1);
if(stage.contains(a1))
removeChild(a1);
if(stage.contains(c1))
removeChild(c1);
if(stage.contains(d1))
removeChild(d1);
if(stage.contains(q1))
removeChild(q1);
}

c1.addEventListener(MouseEvent.CLICK,clickhandler5);
function clickhandler5(event:MouseEvent):void{

q1.visible=false;
a1.visible=false;
b1.visible=false;
c1.visible=false;
d1.visible=false;
if(stage.contains(b1))
removeChild(b1);
if(stage.contains(a1))
removeChild(a1);
if(stage.contains(c1))
removeChild(c1);
if(stage.contains(d1))
removeChild(d1);
if(stage.contains(q1))
removeChild(q1);
}

d1.addEventListener(MouseEvent.CLICK,clickhandler6);
function clickhandler6(event:MouseEvent):void{

q1.visible=false;
a1.visible=false;
b1.visible=false;
c1.visible=false;
d1.visible=false;
if(stage.contains(b1))
removeChild(b1);
if(stage.contains(a1))
removeChild(a1);
if(stage.contains(c1))
removeChild(c1);
if(stage.contains(d1))
removeChild(d1);
if(stage.contains(q1))
removeChild(q1);
}