specification does not match any archived log in the repository - backup cancelled because there are

Hello,

Can someone please tell me why my RMAN script returns following message. Is it a error message OR impormative message? Also there is no error code with it.

Note: We are not using catelog database.

*********************************************************************************

Starting backup at 12-JUL-11using channel ORA_DISK_1specification does not match any archived log in the repositorybackup cancelled because there are no files to backupFinished backup at 12-JUL-11

*********************************************************************************

Please Help!

Jitendra R. Desaria

NUS Consulting Group.

****FOLLOWING ARE THE DETAILS****

Database: Physical Standby

Environment: DataGuard

Oracle: 11gR2

RMAN Configuration:

RMAN configuration parameters for database with db_unique_name ORAPSD are:

CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 2 DAYS;CONFIGURE BACKUP OPTIMIZATION ON;