actionscript3控制flv声音

控制按钮监听事件代码：(省略已定义变量)

public function soundListener(e:MouseEvent):void{
			trace("Sound is changed");
			var st:SoundTransform;
			if(videoStream.soundTransform.volume==0){
				st = new SoundTransform(1,0);
				videoStream.soundTransform = s
			}else{
				st = new SoundTransform(0,0);
				videoStream.soundTransform = st;
			}
			trace(videoStream.soundTransform.volume);
		}

直接修改videoStream.soundTransform.volume=0是没有效果的