From: Dan Knight Dan on
I have 3 unbound comboboxes in the form header that I'm using in sequence to
act as a filtering device for a form.
The first combobox allows the user to select the field for filtering from an
autogenerated list based on the controls in the form's detail section.
The second allows the user to select the criteria based on a hardwired list.
The value list of the 3rd combobox is auto-generated based on the data
entered in chosen field of the form's recordsource. When this combobox is
updated (ie: a value selected) it creates a filter string that filters both
the form and a list box displaying the ID field of the form.

The process works fine when the form is the primary form (ie: opened by
itself), but the form is to reside (unbound) on a main form. In that
situation, the user can select the field and the criteria, but when they
select the value, they receive "The value you selected isn't valid for this
field" error, which may be the case IF the combobox was bound to a field; but
it isn't.