cannot recover copy of database

I've got simple rman backup script:

allocate channel c1 device type disk;
backup incremental level 1 for recover of copy with tag='DB' database; recover copy of database with tag='DB';
release channel c1;
...

Everything works fine until I've started doing some other backups to the tape. Now when I run this script I got error:

RMAN-05019: WARNING: no channel of required type allocated to recover copy of datafile [all_datafile_copies]

I've run crosscheck backup/copy, delete expired, delete obsolete - on device type disk and tape too.

When I list copy of database, everything looks fine, copy is on device type DISK, available etc. Also backup made for recover of this copy is fine and it's on device type disk.

What's wrong?

thanks

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CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 14 DAYS; CONFIGURE BACKUP OPTIMIZATION OFF; # default CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default CONFIGURE CONTROLFILE AUTOBACKUP ON;
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO BACKUPSET; CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE MAXSETSIZE TO UNLIMITED; # default CONFIGURE ENCRYPTION FOR DATABASE OFF; # default CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default

oracle 10.2.0.3, rhel5 Received on Tue Jan 13 2009 - 13:40:49 CST