Turn On Instant Payment Notification
The last thing you need to do is turn on IPN. From your profile summary in your PayPal account:
Click on the Instant Payment Notification link
Click the “Edit Settings” button
Enter the permalink of the store/ipn page on your WordPress website into the Notification URL field in PayPal
Enable the “Receive IPN messages” radio button in PayPal
Click the “Save” button to save your changes
Enabling IPN tells PayPal to alert Cart66 every time the process a sale for you. This causes the sale to be stored in the Orders panel in the Cart66 admin.