Question: I call an asp.net handler (ashx) like this from Flash, and onLoadSuccessful, I get the ashx response back.

The problem now is whatever I do in onLoadSuccessful to get the responseStatus variable never gets me the variable (just an error message: property responseStatus for string not found), but the output of:
trace("Response: " + evt.target.data); is
Response: &responseStatus=ASP.NET+Fehler%3a+Die+Datei+%22C%3a%5cinetpub%5cwwwroot%5cRaumplaner_New%5cRaumplaner_New%5cabcdef.xml%22+konnte+nicht+gefunden+werden.&

It used to work in ActionScript2... Any hints as to what I do wrong ? I mean the request gets sent, and the reponse received, but no matter how I try to do it, I can't access the responseStatus variable...

   var scriptRequest:URLRequest = new URLRequest(strURL);
   var scriptLoader:URLLoader = new URLLoader();
   var scriptVars:URLVariables = new URLVariables();

   scriptLoader.addEventListener(Event.COMPLETE, onLoadSuccessful);
   scriptLoader.addEventListener(IOErrorEvent.IO_ERROR, onLoadError);
   scriptLoader.addEventListener(SecurityErrorEvent.SECURITY_ERROR, onSecurityError);

   scriptVars.ScaleString = nScale;
   scriptVars.ModifyFile = "abcdef.xml";

   scriptRequest.method = URLRequestMethod.POST;
   scriptRequest.data = scriptVars;

   scriptLoader.load(scriptRequest);

   function onLoadSuccessful(evt:Event):void
   {
    trace("Success.");
    //ExternalInterface.call("alert", "Die neue Skalierung wurde erfolgreich gespeichert.");
    //getURL("javascript:alert(\""+"Die neue Skalierung wurde erfolgreich gespeichert.\\nALLE Instanzen des Browsers schliessen und neu starten, damit die Änderung in Kraft tritt."+"\");");

    trace("Response: " + evt.target.data);
    trace("ResponseStatus: " + evt.target.data.responseStatus);
    var loader:URLLoader = URLLoader(evt.target);
    trace("responseStatus: " + loader.data.responseStatus);
   }