Error Testing In-App Purchase

I developed a channel that makes an in-app subscription purchase. It works fine using the fake server (i.e., package-based XML files). I changed the app so that it uses the live Roku store (i.e., by setting store.FakeServer( false)). I packaged and published the private channel. When I try to make a purchase by usng the live store/private channel, I get Roku error screen. That screen says: "Order Problem - There was a problem placing your order (error code 006)."

Do you have any ideas what that might be?