HEAD request to detect updating of files at server

Hi,

I'm trying to send a HEAD request from my AIR for Android Application.

Because, i want download the file only when it has been updated.

I have tried it with URLLoader and HTTPStatusEvent, but the length of reponseHeaders  is 0.

public function dwnLoadIconWheel():void
{
    var urlPub:String = _serverPath + datePath;
    //var urlRequest:URLRequestHeader
    //httpResponseStatus
    var loader:URLLoader = new URLLoader();
    loader.addEventListener(Event.COMPLETE, onPubWheelIconHandler);
    loader.addEventListener(SecurityErrorEvent.SECURITY_ERROR, securityErrorPubWheelIconHandler);
    loader.addEventListener(HTTPStatusEvent.HTTP_STATUS, httpStatusPubWheelIconHandler);
    loader.addEventListener(IOErrorEvent.IO_ERROR, ioErrorPubWheelIconHandler);
    var header:URLRequestHeader = new URLRequestHeader("Created", "2008-06-04T22:45:25Z");
    var request:URLRequest = new URLRequest(_xmlServerEpaperUrl + globalPath);
    trace(request.url);
    request.method = URLRequestMethod.HEAD;
    request.requestHeaders.push(header);
    try {
        loader.load(request);
    } catch (error:Error) {
        trace("Unable to load requested document.");
    }
}
protected function httpStatusPubWheelIconHandler(event:HTTPStatusEvent):void
{
    var loader:URLLoader = URLLoader(event.target);
    loader.removeEventListener(Event.COMPLETE, onPubWheelIconHandler);
    loader.removeEventListener(SecurityErrorEvent.SECURITY_ERROR, securityErrorPubWheelIconHandler);
    loader.removeEventListener(HTTPStatusEvent.HTTP_STATUS, httpStatusPubWheelIconHandler);
    loader.removeEventListener(IOErrorEvent.IO_ERROR, ioErrorPubWheelIconHandler);
    if (event.responseHeaders.length == 0)
        trace("Header length 0");
    else
        trace("Header received");
}

My questions is, if can i get the date of my file from server without download the complete file. Can i do HEAD requests to detect update of files?

Thanks!