I had the very same problem with a HP Tape Drive and a Dell (IBM) TL-2000 tape library.
The problem is the controller. You need to use a plain HBA (without any RAID functionality). I wasted so much time and so many tapes looking for a BE bug or a registry key to be corrected/modified. Currently i'm using a LSI SAS-9207-4i4e HBA without any problem.