Updating worcenter using user exit ZXWOCU07

Hello,

I need to update the fields "Plant" and "Work Center" for each operations when saving an order in IW32.

I know that the user exit that I have to use is ZXWOCU07.

These 2 fields have to be replaced by the values in the header data.

The field "Plant" is updated correctly but "Work Center" always keeps it's old value.

Could any one tell my what I'm doing wrong?

There is the code I use :

CALLFUNCTION'CO_BO_OPR_OF_ORDER_GET'

   EXPORTING

     aufnr_imp = caufvd_imp-aufnr

   TABLES

     afvgd_get = lit_afvgdget.

LOOPAT lit_afvgdget ASSIGNING<l_fs_wa_afvg> .

   <l_fs_wa_afvg>-ARBPL = caufvd_imp-VAPLZ.

   <l_fs_wa_afvg>-WERKS = caufvd_imp-VAWRK.

   <l_fs_wa_afvg>-VBKZ  = 'U'.

endloop.

"Updating operations buffer

CALLFUNCTION'CO_BO_UPDATE_OPR_OF_ORDER'

   EXPORTING

     FLG_NO_SCHED = abap_true

   TABLES

     afvgd_upd = lit_afvgdget.

Thanks a lot for your help