$ oerr rman 6429
6429, 1, "%s database is not compatible with this version of RMAN"
// *Cause: The indicated database is not compatible with this version of
// the Recovery Manager (RMAN). Other messages have also
// been issued which detail the cause of the error.
// *Action: See the other messages. If the database is CATALOG, then you may
// be able to use the CREATE CATALOG or UPGRADE CATALOG commands
// to correct the problem. If the database is TARGET or AUXILIARY,
// then you must either upgrade the target database or use a
// newer version of the RMAN executable.
SMO runs the "rman" binary from the Oracle installation on the target database server - in your case "oraclerac_pr1". The error message seems to be indicating that the version of the "rman" binary on "oraclerac_pr1" does not match the version of the database being used for your RMAN catalog.
If you're not that familiar with Oracle, then I would recommend just not using RMAN - it can be a real pain to set up and use, and (as you see) the error messages are not very helpful when something goes wrong. SMO will work fine without RMAN.
SMO uses the RMAN binaries from the ORACLE_HOME used by target database (the database you want to back up), but your RMAN catalog resides in a database that is a different version of Oracle (10gR1). From what I understand, you cannot do this. Meaning, if you want to use an RMAN catalog to maintain information about a 10gR2 database, then you must create the catalog in a 10gR2 database as well.
One other thing to note... SMO does not support using 10gR1 for its repository (because of numerous bugs in 10gR1).
I would suggest creating the SMO repository and RMAN catalog in a 10gR2 database to solve your problem.