Problem in picking up the value from list box

Question

Hi,
I have created a parameter list box on the selection screen using VRM_SET_VALUES fn module and populating the list box. Now my problem is when i select one value from the list box and executing, it shows null value.
AT SELECTION-SCREEN OUTPUT.
PERFORM f_f4help.
FORM f_f4help .
  REFRESH: gt_tvaut,
           gs_list.
  CLEAR: gs_tvau,
         gs_value.
  SELECT spras
        augru
        bezei
    FROM tvaut
    INTO TABLE gt_tvaut
    WHERE spras EQ sy-langu.
IF NOT gt_tvaut[] IS INITIAL.
    LOOP AT gt_tvaut INTO gs_tvau.
      gs_value-key = sy-tabix.
      CONCATENATE gs_tvau-augru
                  gs_tvau-bezei
             INTO gs_value-text
        SEPARATED BY space.
      APPEND gs_value TO gs_list.
    ENDLOOP.
  ENDIF.
  param = 'P_AUGRU'.
CALL FUNCTION 'VRM_SET_VALUES'
    EXPORTING
      id              = param
      values          = gs_list
    EXCEPTIONS
      id_illegal_name = 1
      OTHERS          = 2.
  IF sy-subrc <> 0.
    MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
            WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
  ENDIF.
How to get the value which  is selected in the selection screen becoz i'm using p_augru in further selection queries..
i have tried reading gs_list table but its not working.

Answer 1

Move the portion of function call 'VRM_SET_VALUES' to event  at selection-screen on value-request for P_AUGRU. Rest is OK...
I mean, Your code should be like this.
AT SELECTION-SCREEN OUTPUT.
PERFORM f_f4help_values.
FORM f_f4help_values.
REFRESH: gt_tvaut,
         gs_list.
CLEAR: gs_tvau,
       gs_value.
SELECT spras
       augru
       bezei
       FROM tvaut
       INTO TABLE gt_tvaut
       WHERE spras EQ sy-langu.
IF NOT gt_tvaut[] IS INITIAL.
  LOOP AT gt_tvaut INTO gs_tvau.
    gs_value-key = sy-tabix.
    CONCATENATE gs_tvau-augru
                gs_tvau-bezei
           INTO gs_value-text
    SEPARATED BY space.
    APPEND gs_value TO gs_list.
  ENDLOOP.
ENDIF.
ENDFORM.
AT SELECTION-SCREEN ON VALUE-REQUEST FOR P_AUGRU.
PERFORM f_f4help.
FORM f_f4help
param = 'P_AUGRU'.
CALL FUNCTION 'VRM_SET_VALUES'
  EXPORTING
    id              = param
    values          = gs_list
  EXCEPTIONS
    id_illegal_name = 1
    OTHERS          = 2.
IF sy-subrc  0.
  MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
          WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
ENDFORM.
Rgds,
Birendra