userexit_field_modification, in me22n komv-kbetr field should be disabled

Hi all,

my Requirement is in me22n puch.org = 6000 and bukrs = 6000 then the ekpo-artilce eq zstd-article and ekpo-werks eq zstd-werks , when condition type "zstd" the amount[komv-kbetr vaule should be disabled....for this i have written the belo code using include LV69AFZZ

form userexit_field_modification.

but when iam trying the below code ekko-ekorg eq '6000' is not getting.kindly help me for this issue

types: begin of ty_ekko,
       ekorg type ekko-ekorg,
       bukrs type ekko-bukrs,
       ebeln type ekko-ebeln,
       lifnr type ekko-lifnr,
       end of ty_ekko.

types: begin of ty_ekpo,
       werks type ekpo-werks,
       matnr type ekpo-matnr,
       ebeln type ekpo-ebeln,
       end of ty_ekpo.

types: begin of ty_zstd,
       werks type  ekpo-werks,
       matnr  type ekpo-matnr,
       end of ty_zstd.

data:it_ekko type ty_ekko occurs 0 with header line,
     wa_ekko type ty_ekko.
data:it_ekpo type ty_ekpo OCCURS 0 WITH HEADER LINE,
     wa_ekpo type ty_ekpo.
data:it_zstd type ty_zstd OCCURS 0 with HEADER LINE,
     wa_zstd type ty_zstd.
if sy-tcode = 'ME21N' or sy-tcode = 'ME22N'.
    If it_ekko-ekorg = '6000'.
       select werks matnr from zstd into table it_zstd.
       select werks matnr ebeln from ekpo into table it_ekpo where werks eq it_zstd-werks
                                                          and matnr eq it_zstd-matnr.
         if it_zstd-matnr eq it_ekpo-matnr and it_zstd-werks eq it_ekpo-werks.

              if komv-kschl = 'ZSTD'.

                  if screen-name = 'KOMV-KBETR'.
                   screen-active = '1'.
                    screen-input = '0'.
                    screen-invisible = '0'.
                   modify screen.
                  endif.
             endif.
         endif.
    endif.
endif.

regards

Suni