Duplicate a database from backup

@duplicate_affnet

HiI am using oracle 11.2.0.3
I did all the steps to duplicate this database from backup disks of the production database

the last stage was:

export ORACLE_SID=AFNSTG
sqlplus / as sysdba
startup nomount pfile=$ORACLE_HOME/dbs/initAFNSTG.ora

rman auxiliary /

RMAN> @duplicate_affnet.rman

than I got the error:

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of configure command at 01/29/2014 07:13:09
RMAN-06136: ORACLE error from auxiliary database: ORA-01507: database not mounted


why? I know that he auxilary db is not mounted, that what I was asked for?

the duplicate_affnet.rman is:

un {
ALLOCATE auxiliary CHANNEL c1 DEVICE TYPE DISK FORMAT "/DBS_EXPORT/AFFNET/Full_Oracle_Backup_AFFNET%U_1_1";