가장 기본적인 ALV 템플릿으로 데이터 조회할 수 있는 프로그램을 만들었는데, 아예 빈화면으로 실행이 안되네요.

제가 놓친 부분이 있는지 확인해 주실 수 있으실까요 ㅜㅜ

*&---------------------------------------------------------------------*
*& Report  ZEX1_3_ABAP_A01
*&
*&---------------------------------------------------------------------*

REPORT z_alv_templete.
INCLUDE z_alv_templete_top.
INCLUDE z_alv_templete_pbo.
INCLUDE z_alv_templete_pai.

INITIALIZATION.

AT SELECTION-SCREEN.

START-OF-SELECTION.

  PERFORM get_data.

END-OF-SELECTION.

  IF sy-subrc EQ 0.
    CALL SCREEN 100.
  ELSE.
    WRITE : '오류 수정 필요'.
  ENDIF.

&---------------------------------------------------------------------*
*&  Include           Z_ALV_TEMPLETE_TOP
*&---------------------------------------------------------------------*

*TYPE-POOLS : slis. <-- 왜 들어가야하는지 이유를 모르겠습니다.

TABLES : ekko.

TYPES : BEGIN OF ty_str,
  ebeln TYPE ekko-ebeln,
  bukrs TYPE ekko-bukrs,
  bsart TYPE ekko-bsart,
  END OF ty_str.

DATA : gs_disp type ty_str.
DATA : gt_disp TYPE TABLE OF ty_str.

DATA : con1_ref TYPE REF TO cl_gui_custom_container.
DATA : g_grid TYPE REF TO cl_gui_alv_grid.

DATA : ok_code TYPE sy-ucomm.

DATA : gt_fieldcat TYPE lvc_t_fcat.
DATA : gs_fieldcat TYPE lvc_s_fcat.

DATA : gs_layout TYPE lvc_s_layo.

*&---------------------------------------------------------------------*
*&  Include           Z_ALV_TEMPLETE_PBO
*&---------------------------------------------------------------------*
MODULE status_0100 OUTPUT.
  SET PF-STATUS '0100'.
  SET TITLEBAR '0100'.
ENDMODULE.                    "status_0100 OUTPUT


*----------------------------------------------------------------------*
*  MODULE set_alv_0100 OUTPUT
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
MODULE set_alv_0100 OUTPUT.
  PERFORM setting_alv_0100.
ENDMODULE.                    "set_alv_0100 OUTPUT
*&---------------------------------------------------------------------*
*&      Form  SETTING_ALV_100
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*  -->  p1        text
*  <--  p2        text
*----------------------------------------------------------------------*
FORM setting_alv_0100 .

  IF g_grid IS INITIAL.

    "인스턴스 생성
    PERFORM create_object.

    "필드카탈로그 생성
    PERFORM set_fieldcatalog.

    "레이아웃 세팅
    PERFORM set_layout.

    "ALV 호출
    PERFORM display_alv.

  ELSE.
    PERFORM refresh_data.

  ENDIF.

ENDFORM.                    " SETTING_ALV_100
*&---------------------------------------------------------------------*
*&      Form  CREATE_OBJECT
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*  -->  p1        text
*  <--  p2        text
*----------------------------------------------------------------------*
FORM create_object .

CREATE OBJECT con1_ref
  EXPORTING
    container_name              = 'con1'.

CREATE OBJECT g_grid
  EXPORTING

    i_parent          = con1_ref.



ENDFORM.                    " CREATE_OBJECT
*&---------------------------------------------------------------------*
*&      Form  SET_FIELDCATALOG
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*  -->  p1        text
*  <--  p2        text
*----------------------------------------------------------------------*
FORM set_fieldcatalog .

  CLEAR : gs_fieldcat.
  CLEAR : gt_fieldcat.

  gs_fieldcat-fieldname = 'EBELN'.
  gs_fieldcat-coltext = '구매문서'.
  gs_fieldcat-key = 'X'.
  APPEND gs_fieldcat TO gt_fieldcat.

  CLEAR : gs_fieldcat.
  gs_fieldcat-fieldname = 'BUKRS'.
  gs_fieldcat-coltext = '회사코드'.
  APPEND gs_fieldcat TO gt_fieldcat.

  CLEAR : gs_fieldcat.
  gs_fieldcat-fieldname = 'BSART'.
  gs_fieldcat-coltext = '문서유형'.
  APPEND gs_fieldcat TO gt_fieldcat.

ENDFORM.                    " SET_FIELDCATALOG
*&---------------------------------------------------------------------*
*&      Form  SET_LAYOUT
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*  -->  p1        text
*  <--  p2        text
*----------------------------------------------------------------------*
FORM set_layout.

  CLEAR : gs_layout.

  gs_layout-zebra = 'X'.
  gs_layout-cwidth_opt = 'A'.
  gs_layout-sel_mode = 'D'.

ENDFORM.                    " SET_LAYOUT
*&---------------------------------------------------------------------*
*&      Form  DISPLAY_ALV
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*  -->  p1        text
*  <--  p2        text
*----------------------------------------------------------------------*
FORM display_alv .

  CALL METHOD g_grid->set_table_for_first_display
  EXPORTING
      is_layout                     = gs_layout
    CHANGING

      it_outtab                     = gt_disp
      it_fieldcatalog             = gt_fieldcat.

ENDFORM.                    " DISPLAY_ALV
*&---------------------------------------------------------------------*
*&      Form  REFRESH_DATA
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*  -->  p1        text
*  <--  p2        text
*----------------------------------------------------------------------*
FORM refresh_data .

CALL METHOD g_grid->refresh_table_display.

ENDFORM.                    " REFRESH_DATA


*&---------------------------------------------------------------------*
*&      Form  get_data
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
FORM get_data.

  CLEAR gt_disp.

  SELECT ebeln bukrs bsart
    INTO CORRESPONDING FIELDS OF TABLE gt_disp
    FROM ekko UP TO 10 ROWS.

ENDFORM.                    " GET_DATA

*&---------------------------------------------------------------------*
*&  Include           Z_ALV_TEMPLETE_PAI
*&---------------------------------------------------------------------*


MODULE exit_0100 input.

  CASE ok_code.
    WHEN 'back' or 'exit' or 'canc'.
      LEAVE PROGRAM.
  ENDCASE.
  ENDMODULE.