Error 1009Cannot access a property or method of a null object

programming flash
1

How do I prevent this error? is is fine until I shift all my content on one frame to create a preloader for the main swf.

I’m using this class called proximitymenu, written by Lee at the Flash Blog.


package
{
	// Import Flash classes
	import flash.display.*;
	import flash.events.*;

	public class ProximityMenu extends MovieClip
	{
		private var ia:Array;
		
		public function ProximityMenu():void
		{
			ia = [eg1Mc, eg2Mc, eg3Mc, eg4Mc, eg5Mc, eg6Mc, eg7Mc, eg8Mc, eg9Mc, eg10Mc];
			for(var i:uint=0; i<10; i++)
			{
				ia*.buttonMode = true;
				ia*.ox = ia*.x;
				ia*.oy = ia*.y;
				ia*.tx = ia*.ox;
				ia*.ty = ia*.oy;
				ia*.addEventListener(MouseEvent.ROLL_OVER, onOver);
			}
			stage.addEventListener(Event.ENTER_FRAME, onMove);
		}
		
		private function onOver(e:MouseEvent):void
		{
			e.target.gotoAndPlay("over");
			addChild(MovieClip(e.target));
		}
		
		private function onMove(e:Event):void
		{
			for(var i:uint=0; i<10; i++)
			{
				var dist:Number =  getDist(mouseX, mouseY, ia*.ox, ia*.oy);
				if(dist < 70)
				{
					ia*.tx = mouseX;
					ia*.ty = mouseY;
				}
				else
				{
					ia*.tx = ia*.ox;
					ia*.ty = ia*.oy;
				}
				ia*.x += Math.round((ia*.tx - ia*.x) * 0.3);
				ia*.y += Math.round((ia*.ty - ia*.y) * 0.3);
			}
		}
		
		private function getDist(x1:Number, y1:Number, x2:Number, y2:Number):Number
		{
			var dx:Number = x2 - x1;
			var dy:Number = y2 - y1;
			return Math.sqrt(dx*dx + dy*dy);
		}
	}
}