# Error Message : Event Handler

**URL:** <https://forum.kirupa.com/t/error-message-event-handler/234100>\
**Category:** flash\
**Created:** [July 30, 2007, 3:39pm UTC](https://forum.kirupa.com/t/error-message-event-handler/234100 "2007-07-30T15:39:15Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Macadia](https://avatars.discourse-cdn.com/v4/letter/m/b2d939/32.png) [@Macadia](https://forum.kirupa.com/u/Macadia)\
**Post date:** [July 30, 2007, 3:39pm UTC](https://forum.kirupa.com/t/error-message-event-handler/234100/1 "2007-07-30T15:39:15Z")

</div>

Hi.  
I have a code designed to move a ball on screen according to mouse positions, but 6 errors are compiled and all say: 1119: Access of possibly undefined property MOUSE\_DOWN through a reference with static type Class.  
for each addEventListener

Code:

package {  
import flash.display.Sprite;  
import flash.events.MouseEvent;

```
public class MouseEvent extends Sprite {
	private var ball:Ball;
	
	public function MouseEvent() {
		init();
	}
	
	private function init():void {
		var ball:Ball = new Ball();
		ball.x = 100;
		ball.y = 100;
		addChild(ball);
		
		ball.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDownBall);
		ball.addEventListener(MouseEvent.MOUSE_UP, onMouseUpBall);
		ball.addEventListener(MouseEvent.MOUSE_MOVE, onMouseMoveBall);
		stage.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDownStage);
		stage.addEventListener(MouseEvent.MOUSE_UP, onMouseUpStage);
		stage.addEventListener(MouseEvent.MOUSE_MOVE, onMouseMoveStage);
		
	}
	
	private function onMouseDownBall(event:MouseEvent):void {
		trace("mouse down &#8211; ball");
	}
	
	private function onMouseUpBall(event:MouseEvent):void {
		trace("mouse down &#8211; ball");
	}
	
	private function onMouseMoveBall(event:MouseEvent):void {
		trace("mouse move &#8211; ball");
	}
	
	private function onMouseDownStage(event:MouseEvent):void {
		trace("mouse down &#8211; stage");
	}
	
	private function onMouseUpStage(event:MouseEvent):void {
		trace("mouse up &#8211; stage");
	}
	
	private function onMouseMoveStage(event:MouseEvent):void {
		trace("mouse move &#8211; stage");
	}
}

```

}

Thanks.