capture report no data(database replay)

-- set filter user : silence

begin
dbms_workload_capture.ADD_FILTER(fname =>'FILTER_TEST',fattribute =>'USER',fvalue =>'SILENCE');
end;
/

-- create 'CAP' directory

-- startup capture

exec dbms_workload_capture.start_capture('sample_cap_name', 'CAP', NULL, 'INCLUDE');

-- check capture
select dbms_workload_capture.report(71, 'TEXT') from dual;

but no data abort workload captured, why not gather workload info ?

For Example:

Database Capture Report For TEST

DB Name         DB Id    Release     RAC Capture Name               Status    
------------ ----------- ----------- --- -------------------------- ----------
TEST          2128451948 11.2.0.3.0  NO  sample_cap_name            COMPLETED 

                   Start time: 05-Nov-13 09:30:52 (SCN = 1273166)
                     End time: 05-Nov-13 09:32:33 (SCN = 1278969)
                     Duration: 1 minute 41 seconds
                 Capture size: 2.44 KB