6i report don't return data through concurrent program

 6i report don't return data through concurrent program. but the main query when run seperate brings the data in TOAD. every thing is correct upto BEFORE REPORT trigger. it also enters into main query but do not select data from the query. I took the trace and verified that query from First UNION is filtering the data but in UNION ALL it gives 0 rows. I have checked for datatypes in main query assuming any data issues, but no luck. No Filter in the report. I am surprised why data is selected in the report but at the time of UNION