Problem in AT selection screen validation

Question

Hi,
I am having problem in AT SELECTION SCREEN Validation.
I have 2 radiobutton and 6 parameter. if i click first radio button  all the 6 radiobutton should enable and take the user input, that is working fine for me.
if i click second radiobutton , out of 6 , 3 parameter should disable and remaining 3 should enable. thats also working fine.
My problem is program has written the validation for this 3 parameter in the AT SELECTION SCREEN.
For first radioutton all the validation working  fine, for second validation as soon as i press the radiobutton it will display error message. Based on 2 parameter user is filling value for 3 rd parameter.
I want the same validation to be done for second radio button after user pressing enter.
PARAMETER: p_single RADIOBUTTON GROUP rad1 DEFAULT 'X' USER-COMMAND f1,
           p_multi RADIOBUTTON GROUP rad1.
PARAMETERS: s_pwwrk LIKE plaf-pwwrk.          
PARAMETERS: p_lgort LIKE plaf-lgort.
PARAMETERS: p_kostl LIKE cobl-kostl.
here is my code:
AT SELECTION SCREEN.
CLEAR t001w.
  CLEAR t001k.
  CLEAR marv.
  SELECT SINGLE * FROM t001w WHERE werks EQ s_pwwrk.
  IF sy-subrc NE 0.
    MESSAGE e999 WITH 'Plant' s_pwwrk 'does not exist'.
  ELSE.
    SELECT SINGLE * FROM t001k WHERE bwkey EQ t001w-bwkey.
    SELECT SINGLE * FROM marv WHERE bukrs EQ t001k-bukrs.
    IF p_budat0(4) NE marv-lfgja OR p_budat4(2) NE marv-lfmon
IF marv-xruem IS NOT INITIAL.
        IF p_budat0(4) NE marv-vmgja OR p_budat4(2) NE marv-vmmon.
MESSAGE e999 WITH p_budat4(2) p_budat0(4)
                            'is closed.
                                        Please try again.'.
        ENDIF.
      ELSE.
        MESSAGE e999 WITH p_budat4(2) p_budat0(4)
                          'is closed.
                                      Please try again.'.
      ENDIF.
    ENDIF.
  ENDIF.

Answer 1

For your Case ,
If i understand clearly,You can do the validation when you want on AT SELECTION SCREEN ON WP_FIELD.
If you say your validation to be done only for Selection of Second Radio Button, then..
AT SELECTION SCREEN.
if p_multi  eq 'X'. "<- Make Validation to be done only if user select Second Button
CLEAR t001w.
CLEAR t001k.
CLEAR marv.
SELECT SINGLE * FROM t001w WHERE werks EQ s_pwwrk.
IF sy-subrc NE 0.
MESSAGE e999 WITH 'Plant' s_pwwrk 'does not exist'.
ELSE.
SELECT SINGLE * FROM t001k WHERE bwkey EQ t001w-bwkey.
SELECT SINGLE * FROM marv WHERE bukrs EQ t001k-bukrs.
IF p_budat+0(4) NE marv-lfgja OR p_budat+4(2) NE marv-lfmon
IF marv-xruem IS NOT INITIAL.
IF p_budat+0(4) NE marv-vmgja OR p_budat+4(2) NE marv-vmmon.
MESSAGE e999 WITH p_budat+4(2) p_budat+0(4)
'is closed.
Please try again.'.
ENDIF.
ELSE.
MESSAGE e999 WITH p_budat+4(2) p_budat+0(4)
'is closed.
Please try again.'.
ENDIF.
ENDIF.
ENDIF.
endif.