using auto validation : order status remains payment_received if user don't return to drupal

Issue Summary

I have configured the effectue/refuse/annule urls.
I have also configured the PBX_REPONDRE_A parameter with the /auto url.

Everything works when the customer returns back from the pay box site via effecue url :
- the order status changes to 'completed'
- stock is modified
- 'Customer get back on successful payment, waiting auto notification to validate payment.' message in the uc_order_comments table

but if he doesn't, for example if he closes the navigator window :
- the order status remains 'payment_received'
- the stock is not modified.
- 'Payment accepted. Paybox transaction id: XXX' in the uc_order_comments table.

There's nothing in the watchdog.