Question on URLFilePromise for dragging remote file out

Question

Now I'm on-going developing an Air desktop application in which remote files need to be dragged out and stored in local file system.
Remote files can be dragged out and stored in local file system in my demo project,however when I merged the demo code to my
app project,it can't work correctly.I find that the URLStream wasn't connected as I registered a function to listen the
    event: Event.OPEN
and the listener function wasn't called.
And also there is no corresponding http request captured with the capture utility:Wireshark.
Could anyone give me some tips to work out the problem.
Thanks a lot!
Below is my code:
private function onMouseDown(event:MouseEvent):void 
var dragAttach:Clipboard = new Clipboard();
if(true == dragAttach.supportsFilePromise)
var filePromise:URLFilePromise = new URLFilePromise();
  var attachURl:String = GlobalConfig.HTTP_SERVER_ADDRESS +
"/" + _srcUname +
"/" + _fileType +
"/src/" + _attachID;
trace(attachURl);
filePromise.addEventListener(Event.OPEN, onURLStreamOpen);
filePromise.addEventListener(IOErrorEvent.IO_ERROR, onError);
filePromise.addEventListener(SecurityErrorEvent.SECURITY_ERROR, onSecrityError)
filePromise.addEventListener(ProgressEvent.PROGRESS, onProgress);
filePromise.addEventListener(HTTPStatusEvent.HTTP_STATUS, onHttpStatus);
//attachURl = "http://192.168.6.229/dragAttach/hello.png";
attachURl = "http://ln.cn/swf/mm.png";
trace(attachURl);
filePromise.request = new URLRequest(attachURl);
filePromise.relativePath = _fileName;
var fileList:Array = new Array();
fileList.push(filePromise);
// only allow the file to be copied
var dragOptions:NativeDragOptions = new NativeDragOptions();
dragOptions.allowMove = false;
dragOptions.allowCopy = true;
dragOptions.allowLink = false;
var setRes:Boolean = dragAttach.setData(ClipboardFormats.FILE_PROMISE_LIST_FORMAT, fileList);
this.addEventListener(DragEvent.DRAG_COMPLETE, onDragComplete);
NativeDragManager.doDrag(this,
  dragAttach,
  _dragImage,
  new Point(-mouseX, -mouseY),
  dragOptions);
return;

Answer 1

yes..EOIO will block the queues if its predecessor are not in final state...
for ur design u can rfer the below wiki...instead of RFC u can use soap adapter..
http://wiki.sdn.sap.com/wiki/display/XI/File-RFC-File%28Without%20BPM%29