Paypal Payment Pending

Paypal integration is not working 100% in astpp. Sometimes a payment shows pending in astpp even though we received the money in our PayPal account. This does not happen with every payment but it does happen quite frequently. Any ideas? ASTPP uses the Paypal Live URL https://www.paypal.com/cgi-bin/webscr which can’t be found in any paypal documentation. Maybe this needs to be updated?