NO workitem created on event requested

dear sir,

I used a function in SWEHR3 to create an event using

CALL FUNCTION 'SAP_WAPI_CREATE_EVENT'
     EXPORTING
       object_type    = 'ZOBJ'
       object_key     = businessobjectkey
       event          = 'REQUESTED'
       commit_work    = 'X'
       event_language = sy-langu.
   COMMIT WORK.

CALL FUNCTION 'SAP_WAPI_WORKITEMS_TO_OBJECT'
    EXPORTING
*     OBJECT_POR                     =
      OBJTYPE                        = lv_objid
      OBJKEY                         = lv_objkey
      TOP_LEVEL_ITEMS                = 'X'
     SELECTION_STATUS_VARIANT       = 0001
*     TIME                           =
      TEXT                           = 'X'
      OUTPUT_ONLY_TOP_LEVEL          = ' '
     LANGUAGE                       = SY-LANGU
*     DETERMINE_TASK_FILTER          = 'X'
*     REMOVED_OBJECTS                = ' '
    IMPORTING
      RETURN_CODE                    = lv_stat
     TABLES
*     TASK_FILTER                    =
       worklist                       = it_wlist
       MESSAGE_LINES                  = it_lines
*     MESSAGE_STRUCT                 =

But the strange this is that the it_wlist is empty and there is no workitem id found.

And when I used SE37, I can see the created workitem, what's seem to be wrong here? is the workitem is not created during the requested event?

Thanks,

Sam