BRBACKUP in SPLITINT Scenario

I want online backup with online_mirror option and the dev_type as util_vol_online.

why brbackup is assuming as util_vol (offline) instead of util_vol_online? and then reports DB is open

./brbackup -t online_ mirror -u / -p initCSV_splitint.sap

BR0051I BRBACKUP 7.20 (31)

BR0169I Value 'util_vol_online' of parameter/option 'backup_dev_type/-d' ignored for 'online_mirror' - 'util_vol' assumed

BR0055I Start of database backup: belhyvpq.anv 2013-05-31 02.44.58

BR0484I BRBACKUP log file: /oracle/CSV/11203/sapbackup/belhyvpq.anv

BR0342E Database instance CSV/SPLIT is open

BR0056I End of database backup: belhyvpq.anv 2013-05-31 02.44.58

BR0280I BRBACKUP time stamp: 2013-05-31 02.44.58

BR0054I BRBACKUP terminated with errors

Thanks in advance.

Regards,

Amit