RMAN ORA-01008: not all variables bound

Recovery Manager: Release 11.2.0.2.0 - Production on Tue Jul 10 10:33:11 2012

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

RMAN> connect target /


DBGSQL:     TARGET> select count(*) into :dbstate from v$parameter where lower(name) = '_dummy_instance' and upper(value) = 'TRUE'
DBGSQL:        sqlcode = 1008
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
ORA-01008: not all variables bound




workaround:

SQL>alter system flush shared_pool;