Error message when trying to connect to rman

I got the following error message when trying to connect to rman:

$ rman target /

Recovery Manager: Release 11.2.0.1.0 - Production on Mon Dec 5 13:53:19 2011
Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.
connected to target database: ORCL (DBID=826177187)
RMAN-06900: WARNING: unable to generate V$RMAN_STATUS or V$RMAN_OUTPUT row
RMAN-06901: WARNING: disabling update of the V$RMAN_STATUS and V$RMAN_OUTPUT rows
ORACLE error from target database:
ORA-19921: maximum number of 128 rows exceeded

Solution:
Check out ps command to see any other rman command connected and if not required kill it.

$ ps -aef|grep rman
oraprod 2093242 2506988   0 13:49:25  pts/3  0:10 rman target /
oraprod 2904212 2613458   0 14:07:43  pts/4  0:00 grep rman

$ kill -9 2093242