Backup Problem BR0278E

Dear Expert,

During DB 13 Full databse backup . I am facing the Error.

BR0103I Following backup volume will be used: DEV_OFF_05

BR0136I Verify option with value 'use_dbv' set - double work to do

BR0148I DBVERIFY will be used for verification

BR0289I BRARCHIVE will be started at the end of processing

BR0134I Unattended mode with 'force' active - no operator confirmation

BR0208I Volume with name DEV_OFF_05 required in device /dev/rmt/1mn

BR0280I BRBACKUP time stamp: 2008-11-21 03.00.34

BR0226I Rewinding tape volume in device /dev/rmt/1m ...

BR0278E Command output of 'LANG=C mt -f /dev/rmt/1m rew':

/dev/rmt/1m: I/O error

BR0280I BRBACKUP time stamp: 2008-11-21 03.00.35

BR0279E Return code from 'LANG=C mt -f /dev/rmt/1m rew': 1

BR0213E Winding tape volume in device /dev/rmt/1mn failed

BR0056I End of database backup: bdzhnlfq.aft 2008-11-21 03.00.35

BR0280I BRBACKUP time stamp: 2008-11-21 03.00.35

BR0054I BRBACKUP terminated with errors

Why this happend. Plesae help

Thanks

manu