Paid subscriptions not working

[cionfs]

Hi,
I've a problem with Paid Subscriptions.

If a member buy a subscription, payment is made but it doesn't move of usergroup.

I've received an IPN Invalid URL: http://www.cionfs.it/forum/payment_gateway.php?method=paypal

I followed this thread but it doesn't work:

http://www.vbulletin.com/forum/showthread.php?255511-Paid-subscriptions-not-working-Check-these-things.

How can I solve this problem?

Bye

Update .

I see this