STATUS CODE: 6 " the backup failed to back up the requested files"

Dear All,

I need you help to resolve my problem,, it is STATUS CODE: 6 " the backup failed to back up the requested files"  when Run Oracle Database backup using RMAN
and the output LOG for failed joj as follow :-

Starting backup at 06-JUL-09
channel ch00: starting incremental level 0 datafile backupset
channel ch00: specifying datafile(s) in backupset
input datafile fno=00005 name=+DATA/racvas/datafile/users.264.656338917
input datafile fno=00007 name=+DATA/racvas/datafile/ivr_data.445.657563073
input datafile fno=00008 name=+DATA/racvas/datafile/ivr_index.449.657647667
input datafile fno=00002 name=+DATA/racvas/datafile/undotbs1.260.656338907
input datafile fno=00012 name=+DATA/racvas/datafile/e_topup_data.724.667928495
input datafile fno=00011 name=+DATA/racvas/datafile/vms_data.760.658229397
channel ch00: starting piece 1 at 06-JUL-09
channel ch01: starting incremental level 0 datafile backupset
channel ch01: specifying datafile(s) in backupset
input datafile fno=00006 name=+DATA/racvas/datafile/indx.344.657536403
input datafile fno=00010 name=+DATA/racvas/datafile/usersindx01.457.657801011
input datafile fno=00004 name=+DATA/racvas/datafile/undotbs2.263.656338915
input datafile fno=00009 name=+DATA/racvas/datafile/usersdata01.456.657800923
input datafile fno=00003 name=+DATA/racvas/datafile/sysaux.261.656338911
input datafile fno=00001 name=+DATA/racvas/datafile/system.259.656338897
channel ch01: starting piece 1 at 06-JUL-09
RMAN-03009: failure of backup command on ch00 channel at 07/06/2009 15:33:51
ORA-19506: failed to create sequential file, name="dbbk_3301_1_691514324", parms=""
ORA-27028: skgfqcre: sbtbackup returned error
ORA-19511: Error received from media manager layer, error text:
VxBSACreateObject: Failed with error:
Server Status: Communication with the server has not been iniatated or the server status has not been retr
ieved from the serve
channel ch00 disabled, job failed on it will be run on another channel
released channel: ch00
released channel: ch01
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ch01 channel at 07/06/2009 15:33:51
ORA-19506: failed to create sequential file, name="dbbk_3302_1_691514324", parms=""
ORA-27028: skgfqcre: sbtbackup returned error
ORA-19511: Error received from media manager layer, error text:
VxBSACreateObject: Failed with error:
Server Status: Communication with the server has not been iniatated or the server status has not been retr
ieved from the serve

RMAN> RMAN>


thanks