Hiding of input field in subscreen

Hi Expertise,

I have to hide some input fields of sub screen after clicking on push button.

related content should display.

IN PBO of subscreen, i have written code which is working for hiding.

other code i have written In PAI of subscreen to display all text field

and input field. which is not working ..

Pbo.

LOOP AT SCREEN.
     IF SCREEN-group1 = 'GRP'.
       SCREEN-INPUT = '0'.
       SCREEN-INVISIBLE = '1'.
     ENDIF.
     MODIFY SCREEN.
   ENDLOOP.

PAI.

IF SY-UCOMM = 'GO'.
  LOOP AT SCREEN .

       IF SCREEN-NAME = 'STUD_ID'.
         SCREEN-OUTPUT = 1.
         SCREEN-ACTIVE = 1.
         SCREEN-INVISIBLE = 1.
         MODIFY SCREEN.
       ENDIF.

       IF SCREEN-NAME = 'ZSTUD_ADD-STUD_ID'.
         SCREEN-OUTPUT = '1'.
         SCREEN-ACTIVE = '1'.
         SCREEN-INVISIBLE = '1'.
         MODIFY SCREEN.
       ENDIF.

       IF SCREEN-NAME = 'ZSTUD_ADD-STUD_ADD'.
         SCREEN-OUTPUT = 1.
         SCREEN-ACTIVE = 1.
         SCREEN-INVISIBLE = 1.
         MODIFY SCREEN.
       ENDIF.

   MODIFY SCREEN .

  ENDLOOP.
  ENDIF.

Please help me out .