as3.0 点击按钮后提示NetConnection.Connect.Closed

我想做一个音频传到rtmp的服务器的flash代码，但是现在是 flash一加载显示NetConnection.Connect.Success，而当点击micBtn按钮的时候却提示NetConnection.Connect.Closed为什么呢？
代码如下：
var con:NetConnection;
var stream:NetStream;
var mic:Microphone;
micBtn.addEventListener(MouseEvent.CLICK,StartAudio);

function StartAudio(e:MouseEvent):void {
con =new NetConnection();
var rtmp:String="rtmp://192.168.249.71/flvplayback";
con.connect(rtmp);
con.addEventListener(NetStatusEvent.NET_STATUS,onConnectStatus);
}

function onConnectStatus(e:NetStatusEvent):void {
trace(e.info.code);
if(e.info.code=="NetConnection.Connect.Success"){
con.client=this; stream=new NetStream(con); //获取麦克风 mic=Microphone.getMicrophone();
Security.showSettings(SecurityPanel.MICROPHONE);
mic.addEventListener(StatusEvent.STATUS,onMicStatus);
stream.attachAudio(mic);
var dateTime:Date=new Date();
var recordName:String=dateTime.getTime().toString();
stream.publish("mp3:"+recordName,"record");
}
}

function onMicStatus(e:StatusEvent):void {
trace(e.code); //允许录音
if (e.code=="Microphone.Unmuted") {
mic.setLoopBack(true);
mic.gain=66;
mic.rate=11;
mic.setUseEchoSuppression(true);
mic.setSilenceLevel(1,-1);
}
}

点击完micBtn 就会弹出一个NetConnection.Connect.Closed 为什么呢？怎么解决呢？