Examine the command output, debug logs, and system logs for a more detailed message on the error.

See "Setting Media Manager debug logging to a higher level" in the NetBackup Logging Reference Guide.

Obtain the list of drives using a method that involves a robotic library query, such as a query available from the robot test utility. Compare the list of drives against the device configuration. Ensure that ltid was stopped and restarted after changes were last made to the device configuration. ltid is the Media Manager device daemon on UNIX and Linux or the NetBackup Device Manager service on Windows.