just screen flashed when i use web.show_document in order to create excel file and send it by url

 HI

forms10g

reports10

windows xp

nothing happens ( screen just flashed ) when i user web.show_document this is my code

SET_REPORT_OBJECT_PROPERTY(report_id, REPORT_DESTYPE,'CACHE');
SET_REPORT_OBJECT_PROPERTY(report_id, REPORT_DESFORMAT,'DELIMITED');
SET_REPORT_OBJECT_PROPERTY(report_id,REPORT_OTHER,'&mimetype=application/x-msexcel');

report_message := run_report_object(report_id, parameter_list_id);
rep_status := report_object_status(report_message);
.

IF rep_status='FINISHED' THEN

WEB.SHOW_DOCUMENT('http://XX.YY.montreal.qc.ca:1999/reports/rwservlet/getjobid9999?server=NAME_SERVER1&mimetype=application/x-msexcel');

*** SCREEN FLASHED WE I PRESSED MY BUTTON TO EXECUTE THIS CODE  WHY ?