AS3 hitTestObject is not working - actionscript-3

Question

I was making flash that moving a circle on my keyboard and creating a flash that hit the wall.
But method 'hitTestObject' is not working...
Hou to solve this ploblem?
import flash.events.KeyboardEvent;
import flash.events.Event;
stage.addEventListener(KeyboardEvent.KEY_DOWN,atKeydown);
stage.addEventListener(KeyboardEvent.KEY_UP,atKeyup);
function atKeydown(e :KeyboardEvent) :void
{
if(e.keyCode == 38) stage.addEventListener(Event.ENTER_FRAME,enterYUp);
if(e.keyCode == 40) stage.addEventListener(Event.ENTER_FRAME,enterYDown);
if(e.keyCode == 37) stage.addEventListener(Event.ENTER_FRAME,enterXLeft);
if(e.keyCode == 39) stage.addEventListener(Event.ENTER_FRAME,enterXRight);
}
function atKeyup(e :KeyboardEvent) :void
{
if(e.keyCode == 38) stage.removeEventListener(Event.ENTER_FRAME,enterYUp);
if(e.keyCode == 40) stage.removeEventListener(Event.ENTER_FRAME,enterYDown);
if(e.keyCode == 37) stage.removeEventListener(Event.ENTER_FRAME,enterXLeft);
if(e.keyCode == 39) stage.removeEventListener(Event.ENTER_FRAME,enterXRight);
}
function enterYUp(e :Event) :void
{
ball.y -= 10;
}
function enterYDown(e :Event) :void
{
ball.y += 10;
}
function enterXLeft(e :Event) :void
{
ball.x -= 10;
}
function enterXRight(e :Event) :void
{
ball.x += 10;
}
if(ball.hitTestObject(wall) == true) trace("!!!!");

Answer 1

function enterYUp(e :Event) :void
{
var bool = checkHit("y", -10); // each frame checks for a hit, returns a Boolean (see the function below)
carryOut(bool, "y", -10); // the movement is carried out based on the Boolean
}
function enterYDown(e :Event) :void
{
var bool = checkHit("y", +10); // you can send the "y" property, and where it wants to go.
carryOut(bool, "y", +10);
}
function enterXLeft(e :Event) :void
{
var bool = checkHit("x", -10);
carryOut(bool, "x", -10);
}
function enterXRight(e :Event) :void
{
var bool = checkHit("x", +10);
carryOut(bool, "x", -10);
}
function checkHit(_prop, _num):Boolean
{
// This single function will run every frame, comparing the balls 'predicted position'
if((ball[_prop] + _num) <= _numCheck)
{
// i might use hitTestPoint instead, but I hate using hitTestObject... it can act weird sometimes.
return true;
}
else
{
return false;
}
}
function carryOut(bool, _prop,_num):void
{
if(bool)
{
trace("hit");
}
else
{
// if the Boolean returned false
// ball[_prop] is ball.x or ball.y depending on if you sent "x" or "y".
// it will ADD the _num you sent, so adding -10 is the same as subtracting.
ball[_prop] += _num;
}
}