BDCDATA for include ZXVEDU04 of EXIT_SAPLVEDA_002?

Question

I am attempting to write my first user exit for an Inbound IDoc. Outbound seems easy by comparison. I am going to add a date to VBAK-MAHDT from an extended ORDERS03 segment. The new IDoc type is called 'Z_EK_ORDERS03' and my extended segment is pretty much like E1EDK03.
I'm working with enhancement VEDA0001. For include ZXVEDU03 of component EXIT_SAPLVEDA_001 I have this so far:
DATA:
  w_z1edk03 LIKE z1edk03,
  w_vbak LIKE vbak.
IF contrl-mestyp = 'ORDERS' AND
  contrl-idoctp = 'Z_EK_ORDERS03'.
  CASE segment-segnam.
    WHEN 'Z1EDK03'.
      IF segment-sdata(3) = 'Z01'.
        w_z1edk03 = segment-sdata.
        MOVE dxvbak TO w_vbak.
        w_vbak-mahdt = w_z1edk03-datum.
        MOVE w_vbak TO dxvbak.
      ENDIF.
    WHEN OTHERS.
  ENDCASE.
ENDIF.
  Now I need to insert the date into the right screen using include ZXVEDU04 of EXIT_SAPLVEDA_002. I have this so far:
DATA:
  x_bdc LIKE bdcdata OCCURS 0,
  w_vbak LIKE vbak,
  w_bdc TYPE bdcdata,
  i_bdc TYPE I.
MOVE dxbdcdata TO w_bdc.
IF w_bdc-fnam EQ SPACE.
  i_bdc = sy-tabix - 1.
  READ TABLE dxbdcdata INDEX i_bdc.
  MOVE dxbdcdata TO w_bdc.
ENDIF.
IF w_bdc-fnam = 'BDC_OKCODE' AND
  w_bdc-fval = 'SICH'.
  CLEAR w_bdc.
  LOOP AT dxbdcdata INTO w_bdc.
    APPEND w_bdc TO x_bdc.
    CASE w_bdc-fnam.
      WHEN 'VBKD-BSTKD'.
        MOVE dxvbak TO w_vbak.
        IF NOT w_vbak-mahdt IS INITIAL.
          w_bdc-fnam = 'VBAK-MAHDT'.
          w_bdc-fval = w_vbak-mahdt.
          APPEND w_bdc TO x_bdc.
        ENDIF.
      WHEN OTHERS.
    ENDCASE.
  ENDLOOP.
  dxbdcdata[] = x_bdc[].
ENDIF.
This gives me an error of 'VBAK-MAHDT does not exist for screen 4001'. Do I have to add BDC records for screen '4351'? If I do what would the OPCODE be? Is there an easier way to accomplish my goals rather than using BDC at all?

Answer 1

OK, I've tried inseting this in various positions of the BDCDATA table but it is not working. With this latest code I get 'No batch input data for screen SAPMV45A 4002' error.
DATA:
  x_bdc LIKE bdcdata OCCURS 0,
  w_vbak LIKE vbak,
  w_bdc TYPE bdcdata,
  n_bdc TYPE bdcdata,
  i_bdc TYPE I,
  done TYPE C.
MOVE dxbdcdata TO w_bdc.
IF w_bdc-fnam EQ SPACE.
  i_bdc = sy-tabix - 1.
  READ TABLE dxbdcdata INDEX i_bdc.
  MOVE dxbdcdata TO w_bdc.
ENDIF.
IF w_bdc-fnam = 'BDC_OKCODE' AND
  w_bdc-fval = 'SICH'.
  CLEAR w_bdc.
  LOOP AT dxbdcdata INTO w_bdc.
    APPEND w_bdc TO x_bdc.
    IF w_bdc-fval = 'KPAR_SUB' AND done IS INITIAL.
      MOVE dxvbak TO w_vbak.
      IF NOT w_vbak-mahdt IS INITIAL.
        n_bdc-program = 'SAPMV45A'.
        n_bdc-dynpro = 4351.
        n_bdc-dynbegin = 'X'.
        APPEND n_bdc TO x_bdc.
        CLEAR n_bdc.
        n_bdc-fnam = 'VBAK-MAHDT'.
        n_bdc-fval = w_vbak-mahdt.
        APPEND n_bdc TO x_bdc.
        CLEAR n_bdc.
        n_bdc-fnam = 'BDC_OKCODE'.
        n_bdc-fval = 'KBES'.
        APPEND n_bdc TO x_bdc.
        CLEAR n_bdc.
      ENDIF.
      done = 'X'.
    ENDIF.
  ENDLOOP.
  dxbdcdata[] = x_bdc[].
ENDIF.
Does anyone have an example of hopw this is supposed to work?