HitTest problem

1

I am working on a project where you have an object that will be dropped on another object and a HitTest performed. But I’m getting the following error. Any ideas on why?

Thanks for any help.


//ERROR:
//TypeError: Error #2007: Parameter hitTestObject must be non-null.
//	at flash.display::DisplayObject/_hitTest()
//	at flash.display::DisplayObject/hitTestObject()

import flash.events.MouseEvent;
import flash.media.Sound
import flash.display.*;

var myLetters:MovieClip = new MovieClip();
var a1:a_letter = new a_letter();
var a_Target:a_letterTarget = new a_letterTarget();

function CreateLetters() 
{
	addChild(myLetters); 
	myLetters.x = -10;
	myLetters.y = 0;
	myLetters.addChild(a1);
	a1.x = 35;
	a1.y = 40;
	a1.name = "a_letter";
	myLetters.addChild(a_Target);
	a_Target.x = 35;
	a_Target.y = 200;
	a_Target.name = "a_letterTarget";
}

CreateLetters();
Main();

var xPos:int;
var yPos:int;

function Main():void
{
	addListeners(a1);
}

function getPosition(target:Object):void
{
	xPos = target.x;
	yPos = target.y;
}

function dragObject(e:MouseEvent):void
{
	getPosition(e.target);
	e.target.startDrag(true);
}

function stopDragObject(e:MouseEvent):void
{
	if (e.target.hitTestObject(getChildByName(e.target.name + "Target")))
	{
	e.target.x = getChildByName(e.target.name + "Target").x;
	e.target.y = getChildByName(e.target.name + "Target").y;
}
else
	{
	e.target.x = xPos;
	e.target.y = yPos;
	}
	e.target.stopDrag();
}

function addListeners(... objects):void
{
	for (var i:int = 0; i < objects.length; i++)
	{
	objects*.addEventListener(MouseEvent.MOUSE_DOWN, dragObject);
	objects*.addEventListener(MouseEvent.MOUSE_UP, stopDragObject);
	}
}