Pushbuttons

Hi,

Can you please assist me.

I am trying to create a program but now the problem that I am having is that my program contains a two pushbuttons, according to the understanding I have, if you press the pushbutton the function code is stored in the ok_code, now the proble is whether I press the pushbutton or not there is nothing stored in the pushbuttons.

I have pasted the coding below, thanx alot for all the help.

REPORT  Z_TEST.
DATA: INPUT(20) TYPE C, OUTPUT(20) TYPE C, OK_CODE TYPE SY-UCOMM,
      SAVE_OK LIKE OK_CODE.


CALL SCREEN 100.

MODULE init_screen_100 OUTPUT.
  CLEAR INPUT.
  CLEAR OUTPUT.
  CLEAR OK_CODE.
ENDMODULE.



MODULE user_command_0100 INPUT.

  WRITE: OK_CODE.
  SAVE_OK = OK_CODE.
  CLEAR OK_CODE.

  CASE SAVE_OK.

  WHEN 'CANCEL_1'.
    LEAVE PROGRAM.

  WHEN 'LOGON_1'.

    WRITE: 'THE USERNAME IS ', INPUT.
    WRITE /.
    WRITE: 'THE PASSWORD IS ', OUTPUT.

   WHEN OTHERS.
     WRITE: SAVE_OK.
     LEAVE PROGRAM.

  ENDCASE.
ENDMODULE.