97->2k conversion unbound combo boxes empty

[Frink]

Hallo,

I've recently converted an Access '97 db app to 2000 and
have run into a problem.
I have a form with unbound combo boxes in the form header
which I use to set up search criteria which updates the
Forms Recordsource when you press a button.
When the record source returns no records (like SELECT *
FROM tblUsers WHERE lngKey=-1") the combo boxes are
blanked after you select an item in them. When there are
records on display, the combo boxes contents appear
correctly.
Using code the values are there, only they are not
displayed.

Any clues?

- Frink