I am having the same issues. I have confirmed that the SATA port the tape drive is connected to is NOT setup as a RAID configuration...the tape drive is supported by Symantec...and Windows does see the tape drive, and it is using the Symantec drivers. I get the following messages when I try to 'add' the device in Backup Exec 11d:
Removing the IDR CD-ROM burner driver (drvmcdb.sys) association for tape drives.
Updating Symantec inf file
Instaling Symantec "04mmdat.sys" for "SCSI\SequentialQUANTUM_DAT___DAT72-000C07A
Driver load failure 0x800F020B for SCSI\SequentialQUANTIUM_DAT___DAT72-000C07A
The device instance does not exist in the hardware tree.
Then I get a second error window:
RSM can not manage library Tape0. The database is corrupt
I have removed and re-installed Backup Exec on the machine, ran all the updates and am still getting the messages. I have not been able to find a solution on Symantec or Quantum's site.