If you run rman and connect to the catalog and try to clone rman will look for the directory where it thinks the correct backup is. You can also do the restore and recovery without the catalog just run rman and connect to the instance that you are cloning to. You will need to have the control files in place and the database mounted. Then you can restore the database.

Code:
RUN {
  ALLOCATE CHANNEL C1 DEVICE TYPE 
    DISK format '/oracle/rman/mydb/bck_20100323';
  RESTORE DATABASE;
  RECOVER DATABASE;
}