Paypal Express Checkout/Interspire shopping cart

Hi, I have an old paypal business account. Several years back i justed used a shopping cart with paypal standard and with great effect. I also created a paypal express checkout account which now needs to be used. I now use Interspire shopping cart. I had the PayPal express script modified previously to refirect users to a certain page on our website if certain SKUs were used. For example if the Sku=123 go to page product.html. This previously worked fine but has stopped working some while ago. I cannot remember exactly, I think for some reason we had to change our paypal account to the paypal express checkout. Im looking for someone with experience in this area who can fix this issue. I have attached some information. Please review the attached. Thanks, Thomas