An error of rman backup.Help!!!!

I used rman with catalog to backup my database.My server os information is :SunOS sf4800 5.7 Generic_106541-10 sun4u sparc SUNW,Ultra-Enterprise
My Oracle RDBMS is 8.1.6.0.0
I used scripts to backup my database. The script is :resync catalog; run{allocate channel ch1 type disk format '/backup/full_%d_%U';
backup (database filesperset 4);
release channel ch1;}
the first work ,but the second have error,and not work.
The error:RMAN-03006: non-retryable error occurred during execution of command: resync
RMAN-07004: unhandled exception during command execution on channel default
RMAN-20003: target database incarnation not found in recovery catalog.
But i did not open the database resetlogs.I think the problem may be :the RDBSM 8.1.6.0.0 should patchset?
the resync catalog work should have some time sleep before run backup step?
I beg your answer.