I've got a proprietary tape drive and BackupExec 9.1 evaluation on XP Pro.
The tape drive reports "IBM 3680" and "DLT" media, and works fine with RSM
and NTBackup.

BackupExec is only able to properly recognize media written with NTBackup,
when I restart all BackupExec services. After that, all operations such as
backup, inventory, erase, etc. fail with "Invalid Physical Tape Library
Parameter" (even with brand new tapes). The catalog operation, when started,
changes its status from Running to Queued and sits there idefinitely. Media
changes are not recognized by BackupExec, while RSM/NTBackup recognizes new
tapes just fine.

When I start BackupExec Device Configuration Wizard, it detects the drive as
unknown and lists "***" as the media type. I select any other media type
from the list, click Next then Finish. However when I open the DevConfig
Wizard again, I see that my selection is not saved. Is this expected?

Does BackupExec create low-level technical logs so that I could track down
the problem? I can see all the SCSI requests coming down to the tape device,
and I see that all the requests are handled.