Warning-Message in START-OF-SELECTION?

Hi there,

I have a question: Isn't it possible to write a warning-message in the start-of-selection-block? I have the following code:

START-OF-SELECTION.


  IF s_matnr IS INITIAL.
    MESSAGE w036(z_mm).
  ENDIF.

  IF p_migo = true.
    MESSAGE w059(z_mm).
  ENDIF.

  SELECT * FROM mara
  [...]

But when I run this program the warning-messages appear as normal errors and not as warnings. Why is this so? I can't understand this behaviour?

I wanna to warn the user if he is selecting to much data because of missing information in the selection-screen...

If I use the AT SELECTION-SCREEN-block, the messages works fine, but the the messages also appear if the user clicks on the extension button of a select-option, and that I wanna to have.

Thank you 😊

Regards

Markus