RMAN Connect error with 11g

Was trying to connect to 11g database using RMAN and getting this error:

/opt/oracle/etc>rman target DP_BACKUP/pass@db_name


RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-00554: initialization of internal recovery manager package failed
RMAN-04005: error from target database:
ORA-01017: invalid username/password; logon denied

The userid/password works fine if I connect using sqlplus as showed below!!!

/opt/oracle/etc>sqlplus DP_BACKUP/pass@db_name

SQL*Plus: Release 11.1.0.7.0 - Production on Wed May 8 09:59:03 2013

Copyright (c) 1982, 2008, Oracle.  All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production

With the Partitioning and Real Application Clusters options

SQL>

User DP_BACKUP has SYSDBA role assigned 

SQL> select * from v$pwfile_users;

USERNAME                       SYSDB SYSOP SYSAS

------------------------------ ----- ----- -----

SYS                            TRUE  TRUE  FALSE

DP_BACKUP                      TRUE  FALSE FALSE

But still errors out!!!

Reason is the password is not in sync with the password file. So, either re-create the password file with appropriate password or change the password for DP_BACKUP user.