//=============================================================================================
public function openForm():void {
//=============================================================================================
	var sendForm:URLLoader = new URLLoader();
	var newFile:FileReference = new FileReference();
	var request:URLRequest = new URLRequest(urlString);
	if (form1.planby.visible && form1.planby.upload.selected) {
		newFile.addEventListener(Event.COMPLETE, responseStatus);
		newFile.upload(request, "attache[attachment]", false);
	} else {
		sendForm.addEventListener(Event.COMPLETE, responseStatus);
		sendForm.load(request);
	}
}

//==========================================================
function responseStatus(e:Event):void {
//==========================================================
	var responseLoader:URLLoader = URLLoader(e.target);
	var responseStati = new URLVariables(responseLoader.data);
	ExternalInterface.call("alert()", responseStati);
	if (responseStati == "yes") {
		openPage("success");
	} else {
		openPage("error");
	}
}


##I also tried
//=============================================================================================
public function openForm():void {
//=============================================================================================
	var sendForm:URLLoader = new URLLoader();
	var newFile:FileReference = new FileReference();
	var request:URLRequest = new URLRequest(urlString);
	if (form1.planby.visible && form1.planby.upload.selected) {
		newFile.addEventListener(HTTPStatusEvent.HTTP_STATUS, responseStatus);
		newFile.upload(request, "attache[attachment]", false);
	} else {
		sendForm.addEventListener(HTTPStatusEvent.HTTP_STATUS, responseStatus);
		sendForm.load(request);
	}
}

//==========================================================
function responseStatus(e:HTTPStatusEvent):void {
//==========================================================
	if (e.status == 200) {
		openPage("success");
	} else {
		openPage("error");
	}
}