Purchase order ME21N ,ME22N Cost center validation against GL

Question

HI,
I'm validating the purchase order cost center against the G/L , if a particular entry is not found against G/L in a custom table
the BADI -ME_PROCESS_CUST_PO Method -->PROCESS_ACCOUNT should raise error message and append in the collector.
i was able to append the error message in the collector and still PO is able to save , but when re-open the PO the error message is cleared from the message collector.
any idea why the message is disappearing from the PO error message collector?
here is my code:
INCLUDE mm_messages_mac.
  DATA: ls_acct TYPE mepoaccounting,
        lt_zgl_cc TYPE zgl_cc,
        ls_customer TYPE mepo_badi_exampl,
        ls_tbsg     TYPE tbsg.
  ls_acct = im_account->get_data( ).
  IF NOT ls_acct-kostl IS INITIAL.
    SELECT SINGLE  * FROM zgl_cc INTO lt_zgl_cc WHERE
                                     glacc      = ls_acct-sakto AND
                                     costcenter = ls_acct-kostl.
    IF sy-subrc NE 0 AND  ls_acct-sakto GE '0000500000'.
      mmpur_message_forced 'E' 'ZM' '048' TEXT-003 ' '  ' ' ' ' .
      CALL METHOD im_account->invalidate( ).
    ENDIF.
    else.
    mmpur_remove_messages_by_id ls_acct-id.
  ENDIF.

Answer 1

Hi,
have you tried to invalidate item instead of account assignment? You can get a reference to item with method GET_ITEM. I can see only one class which implements interface IF_PURCHASE_ORDER_ACCOUNT_MM. It is CL_PO_ACCOUNTING_HANDLE_MM and this class has no code for this method.
Cheers