The following bit of code that you are putting is on the “Thank You” page:
$JAMIntegrate = file_get_contents(“http://www.prontopage.net/affiliates/sale.php?amount=”.$mc_gross.”&trans_id=”.$txn_id.”&custom_mid=”.$_COOKIE.””);
which means you don’t need to transfer the cookie variable to paypal as it can be directly accessed by the following PHP command:
$_COOKIE
so if I understand correctly you just have to specify the total amount and the transaction ID. The cookie part is fine as it is.
I am pretty sure the cookie is set when someone visits your site following an affiliate link. Did you simulate that part to make sure the cookie is set so you can test the commission awarding part?