Can not Run the Report over the web

I have this code to run a reprot from a form over the web but i get this error.
The Report is already added to the reports node in the form moudule.
In Alert :
REP-0503 You did not specify the name of a report
In status Bar:
Frm-40738 Argument 1 to builtin REPORT_OBJECT_STATUS cannot be null

My Code:

DECLARE
rep_id REPORT_OBJECT;
rep_server VARCHAR2(40);
rep_job_id VARCHAR2(200);
rep_status VARCHAR2(100);
BEGIN
rep_id:=FIND_REPORT_OBJECT('report');
set_report_object_property (rep_id,report_destype,cache);
rep_job_id:=RUN_REPORT_OBJECT(rep_id);
rep_status:=REPORT_OBJECT_STATUS(rep_job_id);
Message('after reprot job status--> report_job_id:= '||rep_job_id);
if REP_STATUS = 'FINISHED' then
WEB.Show_Document('http://jalal:8888/reports/rwservlet?Getjobid='||rep_job_id||'&server=test&','_blank');
-- WEB.Show_Document('http://jalal:8888/reports/rwservlet?report=test.rdf&userid=vmsuser/oracle@orcl&destype=cache&desformat=html&pagestream=yes&server=test&','_blank');
else
message('report failed with error message:'||rep_status);
end if;
END;

why i am getting this error message ?

Are you finding 'report'? Is "report" the name of your report? If not, the value is null.

Thanks for your replay.

yes my report name in reports node in the object navigator is report

please replay
thanks

I see you've followed the coding example used in Forms Reference. However, with "Frm-40738 Argument 1 to builtin REPORT_OBJECT_STATUS cannot be null," that says the report name or report id is not found. Put in some alert messages to output values (a troubleshooting technique). For example, after "rep_id:=FIND_REPORT_OBJECT('report');" put in a test to see if rep_id is null

rep_id:=FIND_REPORT_OBJECT('report');
IF rep_id is NULL then
change_alert_message('NOTE','rep_id is null');
ELSE
change_alert_message('NOTE','rep_id is NOT null');
END IF;
btn_id := show_alert('NOTE');
and so on