Shopperpress Paypal Checkout Problem

I’ve added the Checkout and Dashboard pages with their appropriate custom fields, as well as the Paypal gateway code (with my info in place of the example, of course), but all I get on the checkout page is “You have no items in your shopping basket.” no matter how much was there before hitting the “checkout” button.

Here’s the URL of my test installation (ignore the silly domain name):
https://www.peopleplayingwii.com/wordpress/

x-posted @ the Shopperpress support forums.

TIA!