Membership not granting selected subscription after payment completion

I have Membership installed, and I was advised to install BuddyPress in order to edit the registration screen to add the mailing address fields.

When a new user registers and makes a PayPal standard payment with a coupon code, the payment is completed, the user directed back to the "thank you" screen, but their subscription level is not granted. They remain at "visitor" level, with no access to the content.