STREAMS - capture process errors

In the process of configuring a streams environement for bi-directional replication between two oracle databases I get an error at the ' capture phase'.


While Creating capture process at database 1, i.e the package furnished hereunder:

BEGIN
DBMS_STREAMS_ADM.ADD_TABLE_RULES(
table_name => 'gkuser1.tmp',
streams_type => 'capture',
streams_name => 'capture_db1',
queue_name => 'str.strmuser_queue',
include_dml => true,
include_ddl => true);
END;


I am getting the errors as under.

BEGIN
*
ERROR at line 1:
ORA-01422: exact fetch returns more than requested number of rows
ORA-06512: at "SYS.DBMS_STREAMS_ADM", line 75
ORA-06512: at "SYS.DBMS_STREAMS_ADM", line 21
ORA-06512: at line 2

Pl advise
i. What does this error mean?
ii. How to rectify the same ?
iii. Please also advise the initialisation parameters required for setting up the streams envir.

regards
gkrish