This occurs when your school bookstore by accident sells you a product whose price is wrong. When the bookstore asks RedShelf to fulfill it, we can't. Because we don't receive accurate product data, we can't process the URL on our end. It's nobody's fault and we're here to help!
Fill out our BasketID Error form and attach your full, edge-to-edge receipt. With that, RedShelf will make sure you get the code you should've gotten in the store :)