Hi,
Please verify that your drive is in the HCL.
Symantec Backup Exec for Windows Servers (tm) 11d (11.0.6235 and 11.0.7170) Hardware Compatibility List. Includes HCL information for supported drives, libraries, virtual tape devices, fibre-channel HBAs, switches, routers/bridges, VSS, NDMP and iSCSI components. For printing purposes, the latest version of Acrobat is recommended.
Also, make sure that they are up to the latest drivers.
Regards,
Sandra Rodriguez
Advanced Technical Support Engineer