Audio Problem

Hi.  I am testing a very simple audio component built in Flex and am running into an issue with the recording stopping too soon.  Sometimes the recorded audio is blank (0 kb) other times it cuts out portions of the audio or stops prematurely.  I am testing on a MacBook, running Red5 v. 0.7  Can anyone provide any insight on what might be causing this?  Here is the Flex code:

<?xml version="1.0" encoding="utf-8"?>
<mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml" width="215" height="138" creationComplete="init()">
<mx:Script>
        <![CDATA[
                import flash.media.Microphone;
                import flash.events.ActivityEvent;
               
                private var connection:NetConnection;
                private var stream:NetStream;
               
                private function init():void
                {
                        connection = new NetConnection();
                        NetConnection.prototype.onBWDone = function(args) {
                        }

                        connection.addEventListener(NetStatusEvent.NET_STATUS, netStatusHandler);
                        connection.connect("rtmp://localhost/oflaDemo");
                }
       
       private function netStatusHandler(event:NetStatusEvent):void {
            switch (event.info.code) {
                case "NetConnection.Connect.Success":
            recButton.enabled = true;
                break;
            }
        }
               
                private function recordAudio():void
                {
                        var mic:Microphone = Microphone.getMicrophone();
                        mic.setLoopBack(false);
                        mic.rate = 44;
                       
                        stream = new NetStream(connection);
            stream.attachAudio(Microphone.getMicrophone());
            stream.publish("Earshow_" + Math.random(), "record");
                       
                        recButton.enabled = false;

                        stopButton.enabled = true;
                }
               
                private function stopRec():void
                {
                        stream.close();
                       
                        recButton.enabled = true;

                        stopButton.enabled = false;
                }
        ]]>
</mx:Script>
<mx:Button  x="10" y="10" label="Record" id="recButton" click="recordAudio()" enabled="false"/>
<mx:Button  x="84" y="10" label="Stop" id="stopButton" click="stopRec()" enabled="false"/>
</mx:Canvas>