IB_lookupcombo / IB_grid viewing problem


I have a form that contains ib_lookupcombo which use to selecting an
item, other ib_edit for other field and a ib_grid wherein all the
controls have the same datasource. When the user inputs the record by
selecting an item in the ib_lookupcombo it appears to have no problem
all in the ib_grid viewing.

but when an item is selected thur programming ...for example ...
table.fieldbyname('itemid').asstring:=111; the ib_lookupcombo will
appears correctly display the item name that corresponds to the
itemid. but the IB_grid, the field itemname appears to be blank. I
wonder why?