Hello,
Issue is not with the TAPES but communication between BE and the Library.
...Go to the Media TAB, Right Click on the Drive and disable it, right click and delete...follow this step on all the Drives and the Medium changer. Restart BE Services.
Make sure that you have Symantec Drivers for the TAPE Drive and the Medium Changer is Unknown Medium changer in the Device Manager.
Symantec Drivers:
http://support.veritas.com/docs/289147