In standard PBO the field is managed (for vendor, include MF05LO00 module EGMLD_ERMITTELN)
tabbez-bukrs = bseg-bukrs.
tabbez-belnr = bseg-belnr.
tabbez-buzei = bseg-buzei.
readtable tabbez withkey tabbez(17).
if sy-subrc = 0.
tabbez-ind = sy-tabix.
if tabbez-egmld ne space.
rf05l-egmld = tabbez-egmld.
endif.
endif.
* ...
if lfa1-stceg(2) = bseg-stceg(2).
rf05l-egmld = lfa1-land1.
else.
select * from lfas where lifnr = lfa1-lifnr.
if lfas-stceg(2) = bseg-stceg(2).
rf05l-egmld = lfas-land1.
exit.
endif.
So if you want to display something else, you are required to look for some enhancement point executed after this code or in the filling of internal table TABBEZ in module zeile_fuellen, you should start debug once functional confirms the requirement.
Hint Better try to fill bseg-stceg with the BAPI.
Regards,
Raymond