RMAN-06004: ORACLE error from recovery catalog database: RMAN-20020: database incarnation not set

RMAN> backup current controlfile;

Starting backup at 04-APR-10
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup command at 04/04/2010 22:08:50
RMAN-03014: implicit resync of recovery catalog failed
RMAN-06004: ORACLE error from recovery catalog database: RMAN-20020: database incarnation not set

RMAN> reset database;

database incarnation already registered

RMAN> reset database;

database incarnation already registered

RMAN> backup current controlfile;

Starting backup at 04-APR-10
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=134 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
channel ORA_DISK_1: starting piece 1 at 04-APR-10
channel ORA_DISK_1: finished piece 1 at 04-APR-10
piece handle=D:\11GSOFTWARE\FLASH_RECOVERY_AREA\SANDEEP\BACKUPSET\2010_04_04\O1_MF_NCNNF_TAG20100404T221125_5VL041P5_.BKP tag=TAG20100404T221125 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:03
Finished backup at 04-APR-10

Starting Control File and SPFILE Autobackup at 04-APR-10
piece handle=D:\11GSOFTWARE\FLASH_RECOVERY_AREA\SANDEEP\AUTOBACKUP\2010_04_04\O1_MF_S_715471896_5VL04BJP_.BKP comment=NONE
Finished Control File and SPFILE Autobackup at 04-APR-10

RMAN>