How to find Approver of Requisition in oracle Apps R12

SELECT distinct papf.full_name
                   FROM po.po_action_history pah
                      , applsys.fnd_user fu
                      , hr.per_all_people_f papf
                  WHERE object_id = prh.requisition_header_id
                    AND pah.employee_id = fu.employee_id
                    AND fu.employee_id = papf.person_id
                    AND SYSDATE BETWEEN papf.effective_start_date
                                    AND papf.effective_end_date
                    AND pah.object_type_code = 'REQUISITION'
                    AND pah.action_code = 'APPROVE'
                    AND pah.sequence_num =
                           (SELECT MAX(sequence_num)
                              FROM po.po_action_history pah1
                             WHERE pah1.object_id = pah.object_id
                               AND pah1.object_type_code = 'REQUISITION'
                              AND pah1.action_code = 'APPROVE'
                               )