Please verify if the exact make and model of the storage device is listed in the HCL(Hardware Compatibility List) from the following link:
http://support.veritas.com/docs/271383
http://support.veritas.com/docs/271382
If the drive is listed in Veritas HCL, then verify whether Veritas drivers are installed. Drivers other than Veritas driver may not work properly with Backup Exec.
Run "c:\Program Files\VERITAS\Backup Exec\NT\tapeinst.exe" and select "Use VERITAS tape drivers for all tape devices" option. This will install Veritas tape drivers. You may download latest Veritas drivers from the following URL:
http://support.veritas.com/docs/273853
Also refer to the following technote for resolving the issue:
Technote:
http://support.veritas.com/docs/256134
Please perform the following steps to resolve the issue:
1) Delete the device in Backup Exec
2) Restart all Backup Exec services
3) Run device configuration wizard. Please download and install the latest Veritas Device Drivers.
4) Check whether the device is detected and recycle the services.
Hope this helps.