call event function in another event function As3 : i am calling function on another function like below.

    function loadXML(e:Event = null):void{
    	
    	xmlData = new XML(e.target.data);
    	//var production:String = xmlData.production.app_id.text();
    	trace(xmlData);
    	var states:String = xmlData.state.place.text();
    	var desc:String = xmlData.state.description.text();
    	var image:String = xmlData.state.image.text();
    	trace('this is working');	
    }
    obj.addEventListener(MouseEvent.MOUSE_OVER,fl_MouseOverHandler);
    function fl_MouseOverHandler(event:MouseEvent):void
    {
    	loadXML();
    }

in thi s case warning occured `Cannot access a property or method of a null object reference` how do i resolve this?