Prestashop 1.6 Cart recovery after 3DSecure redirect

[jucedupp]

I am building a payment gateway module based on the Authorize.net (aim) module.  The issue is that after 3DSecure validation, it redirects back to the website, but the cart is not in context, I think.  

Before I am redirecting, I am saving the cart id to the session.

It throws the following error:

"Cart cannot be loaded or an order has already been placed using this cart"

This is triggered by:
 

 if (Validate::isLoadedObject($this->context->cart) && $this->context->cart->OrderExists() == false)

on line 188 of classes/PaymentModule.php

How can I load/reload the cart correctly?  

Thanks

Jacques

Edited August 24, 2015 by jucedupp (see edit history)