FlexFileReference.download()无法下载

Question

这样没问题
protected function save_clickHandler(event:MouseEvent):void
{
ownloadURL = new URLRequest();
file = new FileReference();
configureListeners(file);
downloadURL.url = "http://localhost:8080/radar/TempGif/1404293551085.gif";

file.download(downloadURL);
}
-------------------------分割线-------------------
protected function save_clickHandler(event:MouseEvent):void
{
o = remote.getOperation("creatGIF");
o.send(data,"radar",delayTime);
//监听调用成功事件

o.addEventListener(ResultEvent.RESULT,creatGif);
}
private function creatGif(event:ResultEvent):void {
o.removeEventListener(ResultEvent.RESULT,creatGif);

var gifURL:String=event.result as String;
downloadURL = new URLRequest();
downloadURL.url = gifURL;
file = new FileReference();
configureListeners(file);
file.download(downloadURL);
}

这样就没法下载