Developing new payment plugin

I'm developing a new plugin payment to a credit card Italian manager.
I was inspired by paypal plugin.
The function onAfterOrderConfirm and onPaymentNotification is working, in the administration panel the order is confirmed.
But I've a problem, my payment gateway don't call a result url.
the instructions of my gateway tell me to call the notification and then make a redirect.

This is the notify example:

<?php

$paymentID = $_REQUEST['paymentid'];
$result = $_REQUEST['result'];
$auth = $_REQUEST['auth'];
$ref = $_REQUEST['ref'];
$tranid = $_REQUEST['tranid'];
$trackid = $_REQUEST['trackid'];
$details = $_REQUEST['udf1'];
$responsecode = $_REQUEST['responsecode'];

$reply = "REDIRECT=" . "http://www.nomedominio.it/nomecontesto/result.php?paymentid=" . $paymentID;

echo $reply;

?>

at the end of the function onPaymentNotification, after receiving confirmation of payment from the gateway, I do the redirection:



But I'm not going to function after_end, but I go back to the default page, and I get the message empty cart.
In the administration part, I get the correct confirmation of payment, and I also receive the mail order confirmed properly. But I can not display a page with a message of payment confirmed for the user.

The orderId is present, I go to the end of the function.

On the backend I see the order confirmed. You may see on the image attachment.



This is mi function onPaymentNotification:

I deleted the lines

//                    $app = JFactory::getApplication();
//       	    	$app->redirect($return_url, "Grazie per il tuo acquisto"); 

This is my onAfterOrderConfirm:
I don't use "$this->removeCart = true;"



The cart is deleted because on the configuration panel the voice "Clear cart when the order is" is set to Created.
If in this panel I set to Confirmed, at the end of payment procedure the browser return to Checkout with the cart full.
On the administrator panel the order is Confirmed, but on front-end it seems that nothing has happened.

Excuse me, I finally discovered that the error in question is made from my payment gateway that calls the url of notification and after the url of cancellation.
Thank you for your patience.