Camera.getCamera(); 显示为黑屏啊哪位大哥知道是咋回事啊求

Camera.getCamera(); 显示为黑屏啊。哪位大哥知道是怎么回事啊。急求

Java code

<?xml version="1.0" encoding="utf-8"?><mx:Application initialize="{vedioi()}" xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">    <mx:Script>        <![CDATA[            import flash.media.Camera;            private function vedioi():void            {                var cam:Camera= Camera.getCamera();                vid.height=360;                vid.width=360;                vid.attachCamera(cam);                lb.text="已经启动";            }        ]]>    </mx:Script>    <mx:VideoDisplay x="92" y="69" width="284" id="vid" height="233"/>    <mx:Label x="216" id="lb" y="342" text="Label"/></mx:Application>