I was testing my a payment with paypal in sandbox mode and the first thing I wanted to test was if someone cancelled the transaction how would it return to the website. Something is apparently wrong with the cancel url because if I cancel a payment it doesn't return to the proper payment page for an invoice and it throws a error. The GET value for my payment id is 1, but when I cancel the paypal payment it returns with the url have a GET value for my payment as 0. Why is it not returning to the proper page and how can I fix this?