Veritas netbackup server 6.0

Question

After backup completes my tape drive goes down! its a wondows 2003 server with veritas netbackup server 6.0 is running! the error i found in the application event id 2636 description is
Operator/EMM server has DOWN'ed drive SEAGATE.ULTRIUM06242-x*x.000 (device 0)
Operator/EMM server has DOWN'ed drive SEAGATE.ULTRIUM06242-x*x.000 (device 0)
and no event id for this error ---
emmlib_UpdateDriveRuntime failed, status=328, retry next scan cycle.
Please can you help me on this