Hello,
To resolve the issue please do the foll steps:
1.Please confirm that the device is in the compatibility list :
http://support.veritas.com/docs/271383
if yes then please install the latest Veritas drivers with the help of the link below:
VERITAS Backup Exec (tm) 9.1 - Device Driver Installer (20050115) - Includes Tape Driver Release (20041231) and Robotic Library Release
http://support.veritas.com/docs/273853
2.If the above provided solution does not work please delete the device and re-create it with the following steps:
1.Open Backup Exec click on the devices tab Right-click the device that you are using, and click Properties
2.Click the Configuration tab, clear the Enable for Backup Exec checkbox, and click OK. The device will be disabled now.
3. Right-click the device, and click Delete
4. Now Power off the device and shut down the server
5. Next power on the device wait for it to initialize and then reboot the server and recycle the Backup Exec services again.
Additional information:
How to troubleshoot issues with a Robotic Library or Tape Drive in Backup Exec 9.x for Windows Servers
http://support.veritas.com/docs/255501
Thanks,