Payment Button Integration

Hello, I have a website with a members area that was set up by a programmer to include a registration page, login page and a secure members area. Payments are set up through paypal, as soon as payment is done customers are re-directed to registration page which only gives access when they’re transferred from the paypal page or else re-directs them to another page, so that not just anyone can register on the site without paying.

Now I am using www.paydotcom.com which will manage my affiliates and I need to integrate their button for them to be able to track my affiliates, calculate and pay their commission. I have a section to enter the variables and/or settings for that button and I am already provided with the button according to the settings I have entered. Their button redirects customers to paypal, from where they make the payment, and then redirects them to a ‘thank you URL’ which I set as the registration page.

Now if I test the paydotcom button I am properly re-directed to paypal and can make the payment. But after the payment is done, if I try to return to my site to register, it re-directs me to the main page. Even after I made a payment, I tried entering the registration page URL in my address bar, and I am re-directed to the main page again.

Now I have minimal php knowledgde as I built the site in html, and all of the pages used for the secure members area are in php.

But I can tell that its a problem with the coding in the registration page as I am re-directed to paypal and can make the payment for the right product (my site) but I am not re-directed to the registration page which is not giving me access since I’m not transferred directly from paypal anymore.

I need someone to fix that for me. I will give you access to my paydotcom account as well as my host so that you can see all of the files and coding for the members area on my host as well as the settings entered in my paydotcom account. It shouldn’t take long as everything is already set up, I just need the code that validates access to customers to be modified. I think that should fix it.