I have installed RMAN catalog on a 8.1.7 database and am trying to register an 8.1.6 database. I get the following messages:

Recovery Manager: Release 8.1.7.0.0 - Production

RMAN-06186: PL/SQL package SYS.DBMS_RCVMAN version 08.01.06 in TARGET database is too old RMAN-00571: ===================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===================
RMAN-00554: initialization of internal recovery manager package failed
RMAN-06429: TARGET database is not compatible with this version of RMAN

Would anyone know how to resolve this? I have looked at the compatibility table and thought everything was ok. How do I find out my version of RMAN executable and catalog schema?

Thank you.