Need help for RMAN backup

Hi
My RMAN backup of one database is failing with the following error

RMAN> #run {
2> #set command id to 'rman';
3> #}
4> # Database backup
5>   backup incremental level 1 cumulative
6>        tag database_backup
7>           format '/drcd03/rcd/o01rcd3dump/rman/O01RCD3_%s_%p_%T_%t.bak' database;
Starting backup at 07-JUN-13
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup command at 06/07/2013 23:30:16
RMAN-12001: could not open channel ORA_DISK_1
RMAN-10008: could not create channel context
RMAN-10003: unable to connect to target database
RMAN-04022: target database mount id 2967608579 does not match channel's mount id 2968049527

RMAN>        crosscheck archivelog all;
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============