Restore backup job

I recently backed up to tape using NT Backup on a Windows 2003 server. The backup ran well and I can see the files on the tape when checking on the server from which the tape was backed up. However, when I took the tape offsite to try and restore it, the server there with the same hardware and software specifications could not see the media. I tried using both NT backup and backup Exec but both could not see the media. Is there something I’m missing?