Need to add request set to request group from Back end.

Hi..

I want to add a request set from back end to a Request Gropup and i tried in the below format 

begin                                  set name                                      ,   set appl ,   req group ,  req group appl  FND_set.add_set_to_group('Oracle Exchange Customer Import','Receivables',  'test_RG',    'Receivables'); end; But I am getting a error as "ORA-06501: PL/SQL: program error
ORA-06512: at "APPS.FND_SET", line 166
ORA-01403: no data found
ORA-06512: at "APPS.FND_SET", line 1578
ORA-06512: at line 2
" So please let me know what the problem was. Thanks.

end;

But I am getting a error as

"ORA-06501: PL/SQL: program error