i have tried to backup oracle 11g db with symantec backup exec 12 but failed with following message

connected to target database: TEST (DBID=1962509789)

using target database control file instead of recovery catalog
allocated channel: ch0
channel ch0: SID=199 device type=SBT_TAPE
channel ch0: Symantec/BackupExec/1.1.0

sent command to channel: ch0

Starting backup at 16-JUL-09
current log archived
released channel: ch0
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup plus archivelog command at 07/16/2009 13:27:28
RMAN-06059: expected archived log not found, lost of archived log compromises recoverability

ORA-19625: error identifying file F:\ORA_ARCHIVE\TEST\ARC001_02573_0664363362.LOG
ORA-27041: unable to open file
OSD-04002: unable to open file
O/S-Error: (OS 2) The system cannot find the file specified.

Recovery Manager complete.