Cancel in not working on Screen

Question

Hello All,
I am writing a data entry program.  I am stuck........ once the user enters incorrect data - the cancel and back buttons don't work.  I thought I was following the example SAP provided, but my code doesn't work the way the examples does.
Could someone please take a look and see if you can see where I am going wrong.  Here is a portion of my code.....
                     Ticket Entry                                  *
CALL SCREEN 200.
                        MODULES                                    *
PBO  Proccess before output
MODULE PBO_0200 OUTPUT                                             *
MODULE pbo_0200 OUTPUT.
  SET PF-STATUS 'MAIN'.
  SET TITLEBAR '200'.
  CLEAR zinv_mm_count.
  zinv_mm_count-mandt = 003.
  zinv_mm_count-werks = 1000.
  zinv_mm_count-lgnum = 100.
ENDMODULE.                    "PBO_0200 OUTPUT
PAI  Proccess after input
MODULE CANCEL INPUT                                                *
MODULE cancel INPUT.
  LEAVE PROGRAM.
ENDMODULE.                    "cancel INPUT
MODULE BACK INPUT                                                  *
MODULE back INPUT.
  LEAVE TO SCREEN 0200.
ENDMODULE.                    "back INPUT
MODULE TICKET INPUT                                                *
MODULE ticket INPUT.
  SELECT SINGLE * FROM ztickets
         WHERE zticket = zinv_mm_count-zticket.
  IF sy-subrc EQ 0.
    CASE ztickets-zstatus.
      WHEN 'V'.              "Ticket has been voided
        MESSAGE e000(ztic).
      WHEN 'E'.              "Ticket has been entered
        MESSAGE e001(ztic).
      WHEN 'C'.              "Ticket has been completed
        MESSAGE e002(ztic).
      WHEN 'OTHERS'.
    ENDCASE.
  ELSE.                      "Ticket number is invalid
    MESSAGE e003(ztic).
  ENDIF.
ENDMODULE.                    "TICKET INPUT
MODULE PLANT INPUT                                                 *
MODULE plant INPUT.
  SELECT SINGLE * FROM t001w
         WHERE werks = zinv_mm_count-werks.
  IF sy-subrc NE 0.
    MESSAGE e004(ztic).
  ENDIF.
ENDMODULE.                    "PLANT INPUT
Flow Logic on the Screen........
PROCESS BEFORE OUTPUT.
  MODULE pbo_0200.
PROCESS AFTER INPUT.
  MODULE CANCEL AT EXIT-COMMAND.
  MODULE BACK   AT EXIT-COMMAND.
  FIELD zinv_mm_count-zticket MODULE ticket.
  FIELD zinv_mm_count-werks   MODULE plant.
  FIELD zinv_mm_count-lgnum   MODULE whse.
  FIELD zinv_mm_count-lgort   MODULE sloc.
  FIELD zinv_mm_count-lgtyp   MODULE styp.
  FIELD zinv_mm_count-lgpla   MODULE sbin.
  FIELD zinv_mm_count-charg   MODULE batch.
  FIELD zinv_mm_count-matnr   MODULE part.
  FIELD zinv_mm_count-menge   MODULE qty.
  MODULE pai_0200.
  Thanks!
Helen

Answer 1

Go to the gui status,  drop down the function keys node on this screen,  you will see the buttons for top level navigation(save, back, exit, cancel).  Now double click on the back button,  you will get a dialog.  Now you need to enter "E" for the functional type, do the same for the cancel,  save and activate.
Regards,
RIch Heilman