Dragging problem!?

I want to drag items on to their places but when I dragged them they become visible and go to place that i do not want

the code is below what is the error?


package  {
	import flash.events.MouseEvent;
	import flash.display.MovieClip;
	
	public class bolmemakinem extends MovieClip{




			var xyeri:Number;
			var yyeri:Number;
			
		public function bolmemakinem() {
			
			// constructor code
			a01.yer=makine.b01;
			a02.yer=makine.b02;
			a03.yer=makine.b03;
			a04.yer=makine.b04;
			
			
			a01.addEventListener(MouseEvent.MOUSE_DOWN,surukle);
			a02.addEventListener(MouseEvent.MOUSE_DOWN,surukle);
			a03.addEventListener(MouseEvent.MOUSE_DOWN,surukle);
			a04.addEventListener(MouseEvent.MOUSE_DOWN,surukle);
			a01.addEventListener(MouseEvent.MOUSE_UP,birak);
			a02.addEventListener(MouseEvent.MOUSE_UP,birak);
			a03.addEventListener(MouseEvent.MOUSE_UP,birak);
			a04.addEventListener(MouseEvent.MOUSE_UP,birak);
		}
		function surukle(e:MouseEvent){
			xyeri=e.target.x;
			yyeri=e.target.y;
			e.target.startDrag();
		}
		function birak(e:MouseEvent){
			e.target.stopDrag();
			if (e.target.hitTestObject(e.target.yer)){
				e.target.x=e.target.yer.x;
				e.target.y=e.target.yer.y;
				e.target.mouseEnabled=false;
				
			}
			else {
				e.target.x=xyeri;
				e.target.y=yyeri;
			}
			
		}
		
		


	}
	
}