为什么我的URLLoader在完成后没有调度？

我正在使用URLLoader将一些键/值对发送到php脚本,然后将其转换为电子邮件,发送(或不发送),然后使用响应回显字符串.

起初它工作正常.URLLoader发布,一分钟后我收到了我的电子邮件,但由于某种原因,我没有得到我的回复.事实上,我的COMPLETE事件似乎根本没有发生.这让我感到困惑,因为如果我收到我的电子邮件,我知道我必须正确发送所有内容.这是我的代码:

public class Mailman{
    public static const METHOD:String = URLRequestMethod.POST;
    public static const ACTION:String = "mailer.php";

    public static var myLoader:URLLoader = new URLLoader();

    private static function onMessageProgress(e:Event){
        var L:URLLoader = e.target as URLLoader;
        Output.trace("PROGRESS: "+L.bytesLoaded+"/"+L.bytesTotal);
        for(var k in L){
            Output.trace("   "+k+": "+L[k]);
        }
    }

    private static function onOpen(e:Event){
        Output.trace("Connection opened");
    }

    private static function onComplete(e:Event){
        Output.trace("Complete!");
    }

    private static function onStatusChange(e:HTTPStatusEvent){
        Output.trace("Status Changed to "+e.status);
    }

    private static function onMessageFail(e:Event){
        PanelManager.alert("ERROR: Could not send your request. Please try again later.");
    }

    public static function sendMessage(recipient:String,subject:String,message:String){
        var _vars:URLVariables = new URLVariables();
            _vars.recipient = recipient;
            _vars.subject = subject;
            _vars.message = message;

        var req:URLRequest = new URLRequest(ACTION);
        req.data = _vars;
        req.method = METHOD;

        myLoader.dataFormat = URLLoaderDataFormat.VARIABLES;
        myLoader.addEventListener(ProgressEvent.PROGRESS,onMessageProgress);
        myLoader.addEventListener(Event.OPEN,onOpen);
        myLoader.addEventListener(Event.COMPLETE,onComplete);
        myLoader.addEventListener(HTTPStatusEvent.HTTP_STATUS,onStatusChange);
        myLoader.addEventListener(IOErrorEvent.IO_ERROR,onMessageFail);
        myLoader.addEventListener(SecurityErrorEvent.SECURITY_ERROR,onMessageFail);
        myLoader.load(req);
    }

    public static function test(){
        sendMessage("john@example.com","test","this is a test message.");
    }

    function Mailman(){}
}

当我打电话时Mailman.test(),我收到的电子邮件完全像我期望的那样,这就是追踪:

    Connection opened
    PROGRESS: 45/45
    Status Changed to 0

怎么会这样？如果我正确理解文档,Open事件发生在我开始下载我的响应时,并且显然正在发生,那么如何才能获得http状态为0？有任何想法吗？