FPM Dialog Box: handling error on press ok

Dear Colleagues and Experts,

This is the code snippet:

method if_fpm_guibb_form~process_event.
  data lv_action_button type string.
  case io_event->mv_event_id.
    when cl_fpm_event=>gc_event_close_dialog_box.

      io_event->mo_event_data->get_value(
        exporting
          iv_key   = 'DIALOG_BUTTON_ACTION'
        importing
          ev_value = lv_action_button ).

      if lv_action_button = 'OK'.
        et_message = do_some_check( ).
      endif.

    endcase.

endmethod.

Event though the method do_some_check( ) returns some error message with severity error, the dialog box is still closed and the error message is not shown anywhere.

Can you help me here please.

Best regards,

Steve Sandrio