wall.post

[AlexCooper]

Здравствуйте.
Нужно добавить к публикации картинки (на стенку пользователя) её описание. Использую контейнер.

private function setUploadURL(data:Object):void {
 
	cache.uploadURL = data.upload_url;
	cache.mid = data.mid;
	cache.aid = data.aid;
 
	var header:URLRequestHeader = new URLRequestHeader("Content-type","application/octet-stream");
	var loader = new URLLoader();
	var jpg:JPGEncoder = new JPGEncoder(100);
 
	var ba:ByteArray = new ByteArray();
 
		ba = jpg.encode( extractBmpd(cache.viralsprite, 0, 0 , cache.viralsprite.width, cache.viralsprite.height) );
 
	var urlRequest = new URLRequest(cache.uploadURL);
		urlRequest.method = URLRequestMethod.POST;
 
		urlRequest.requestHeaders.push(new URLRequestHeader("Content-type", "multipart/form-data; boundary=" + MultipartData.BOUNDARY));
 
 
	var urlLoader = new URLLoader();
		urlLoader.addEventListener(Event.COMPLETE, urlLoader_completeHandler);
		urlLoader.addEventListener(Event.OPEN, urlLoader_openHandler);
 
	var bitdata:MultipartData = new MultipartData();
        bitdata.addFile(ba, "photo");
 
        urlRequest.data = bitdata.data;
         urlLoader.load(urlRequest);
}

private function urlLoader_completeHandler(event:Event):void {
	var callback:Object = JSON.decode(event.target.data);
	wrapper.external.api("photos.saveWallPhoto",{server:callback.server,photo:callback.photo, hash:callback.hash}, resultVKUpload, onApiRequestFail);
}

private function resultVKUpload(data:Object):void {
	wrapper.external.api("wall.post",{owner_id:uid,message:"Text in pist",attachments:data[0].id}, post_ok, post_cancel);
}

Подскажите где искомый параметр.