stage没办法设置监听

Java code

<?xml version="1.0" encoding="utf-8"?><s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/mx"creationComplete="init(event)" >                        protected function init(event:FlexEvent):void            {                stage.addEventListener(MouseEvent.CLICK,test);            }                        private function test(event:MouseEvent):void{                Alert.show("cc");            }

报错 :Cannot access a property or method of a null object reference
为什么stage没办法addEventListener,不管设置什么监听的会报这个错误



[解决办法]
写错地方了。给场景加一个addto事件，在函数体里就可以用stage了。