How to run or call a report from custom form in oracle apps Using fnd_request.submit_request

Write The code in Report Button using Trigger
WHEN-BUTTON-PRESSED

DECLARE
   ln_request_id     NUMBER;
   lc_boolean       BOOLEAN;
BEGIN

   IF :xxopm_wr_hdr.WORK_REQUEST_NO IS NULL
   THEN
      fnd_message.DEBUG ('WORK REQUEST NO is blank.!!! Printing is not possible');
      RAISE form_trigger_failure;
   END IF;

  --Set Layout
  lc_boolean :=
                   fnd_request.add_layout (
                            template_appl_name   => 'XXCUST',             -- Template Application Short Name
                            template_code        => 'XXOPM_WRRPT',     -- Template Code
                            template_language    => 'en',                     -- Use language from template definition
                            template_territory   => 'US',                     -- Use territory from template definition
                            output_format        => 'PDF'                     -- Use output format from template definition
                                    );
   ln_request_id :=
                          fnd_request.submit_request
                                                          ('XXCUST',                                    -- Application Short Name
                                 'XXOPM_WRRPT',                                            -- Program Short Name
                                 'Work Request Report',                        -- Description   
                                 Sysdate,                                      -- Start Time
                                 FALSE,                                            -- Sub Request
                                 :XXOPM_WR_HDR.WORK_REQUEST_NO          -- User Parameter used in Report.
                                 );
   COMMIT;
   FND_MESSAGE.DEBUG ('Request Submitted Successfully.!!! with '||:xxopm_wr_hdr.WORK_REQUEST_NO);
  
EXCEPTION WHEN NO_DATA_FOUND THEN
          FND_MESSAGE.DEBUG ('Concurrent request failed to submit BEACUSE NO DATA FOUND');

   IF ln_request_id = 0
   THEN
      FND_MESSAGE.DEBUG ('Concurrent request failed to submit');
   ELSE FND_MESSAGE.DEBUG ('Request Submitted Successfully.!!!');
   END IF;
  
END;