Backup is failing daily...

Hi Friendz

One of my client had a problem in taking backup.It is failing with the follow error

Please help me guys it seems like critical daily backup is failing from three days.

Backup function Start of backup End of backup RC Log

all, online, tape 11.12.2008 21:30:09 11.12.2008 21:30:58 0005 bdzlmrfl.ant

BR077I Database file for backup: /oracle/SID/sapbackup/cntrlSID.dbf

BR061I 60 files found for backup, total size 192469.195 MB

BR143I Backup type: online_cons

BR113I Files will be compressed by hardware

BR130I Backup device type: tape

BR102I Following backup device will be used: /dev/rmt/1mn

BR104I 1 scratch volume will be used

BR289I BRARCHIVE will be started at the end of processing

BR134I Unattended mode with 'force' active - no operator confirmation allowed

BR237I Scratch volume required in device /dev/rmt/1mn

BR280I Time stamp 2008-12-11 21.30.12

BR226I Rewinding tape volume in device /dev/rmt/1m ...

BR351I Restoring /oracle/SID/sapbackup/.tape.hdr0

BR355I from /dev/rmt/1mn ...

BR241I Checking label on volume in device /dev/rmt/1mn

BR280I Time stamp 2008-12-11 21.30.53

BR226I Rewinding tape volume in device /dev/rmt/1m ...

BR202I Saving /oracle/SID/sapbackup/.tape.hdr0

BR203I to /dev/rmt/1mn ...

BR278E Command output of 'LANG=C cd /oracle/SID/sapbackup && echo .tape.hdr0 /usr/sap/SID/SYS/exe/run/brtools -f detach LANG=C cpio -ovB > /d

sh: /dev/rmt/1mn: Cannot create the specified file.

BR280I Time stamp 2008-12-11 21.30.58

BR279E Return code from 'LANG=C cd /oracle/SID/sapbackup && echo .tape.hdr0 /usr/sap/SID/SYS/exe/run/brtools -f detach LANG=C cpio -ovB > /de

BR222E Copying /oracle/SID/sapbackup/.tape.hdr0 to/from /dev/rmt/1mn failed due to previous errors

BR221E Writing volume header files to /dev/rmt/1mn failed

BR056I End of database backup: bdzlmrfl.ant 2008-12-11 21.30.58

BR280I Time stamp 2008-12-11 21.30.58

BR054I BRBACKUP terminated with errors