Upgrade Level on Successful CB Checkout

Hi

I am busy implementing S2 for our membership site. The site offers video e-learning courses.
A key requirement for us is that the customer registers first and then pays.
I have a scenario / flow as follows which requires the membership to upgrade from level 3 to 4 on successful purchase:

1.Customer registers through a Proform to Level3
2.He is automatically logged in (I applied the “hack” supplied on the forum) and it says thank you for registering please pay now. I generated a Clickbank button for level 3. (Yes I have also tried Level4 button)
3. He goes to Clickbank checkout and makes payment successfully and is redirected back to the site

The problem is he still remains on Level 3. I have also tried a level 4 button. The payment goes through but he is not upgraded. Please note the customer has not paid to be on level 3 yet i.e. he is still free and now paying to become a level 4.

I am sure I am missing something simple here.
Please help, I have been trying to resolve this for 2 days.

Thanking you in advance.

Hi to All

So I finally answered my own question and it was something super simple.
The key to success was in Clickbank the IPN URL had to be set to version 2.1 as opposed to the standard version 1.0.

I hope this helps anyone else out there that might encounter this problem.

Cheers

Glad you figured it out. Thanks for the update! :)