Syncro combo problem

[Mike Grimwood]

My access 97 uses a syncro combo to select a category
then a sub-category, both with No 1 col bound, prior to
running a qry filter - works well. However, on
convertion to 2000 the first box fails to display the
selection, the second box displays the correct sub-
categories, but again will not display the selection.
Consequently the qry filter fails to start. Can anyone
help.