ORA-27046 during RMAN backup

Hi
we are trying to run cold back using RMAN on our 10.2.0.2 database on AIX 5.3 64 bit but are getting ORA-27406

here is what we are running

configure channel device type disk clear;
configure channel device type sbt clear;
configure device type disk backup type to backupset;
configure channel 1 device type disk format '/oracle/rmanbackup/%U' maxpiecesize 2048 M;
configure controlfile autobackup on;
configure controlfile autobackup format for device type disk to '/oracle/rmanbackup/cfspf_%F';
shutdown immediate;
startup mount;
run
{
backup database;
}
alter database open;


Here are the error details
 
input datafile fno=00016 name=/kcustoms/oradata/kff_accpac/kewillfwd_KFF_STAGING.ora