Ask bookstore for their IP address. Review IP address in the API Partner section of Back Office (API Partner section is located in the Configuration top navigation item). If the IP address in Back Office does not match what the bookstore is saying, then create a new IP address range for that bookstore. Ask Bookstore to try again.
If the IP address is correct in BO, then ask bookstore for the Catalog API (XML API) call it is making to CourseSmart. After receive information, confirm the program ID that is being referenced in the API call matches the program ID in Back Office for that store. Confirm the Program ID has a valid library associated with it.
If still can't figure out the information, send all the information including API call and any troubleshooting steps you have already tried to Solutions team at firstname.lastname@example.org.