I am creating a parent ComboBox class. I want it to automatically disable when nothing is in the combobox; in other words,

ComboBox.Enabled = (ComboBox.ListCount > 0)

I have tried putting the above code into the When, Requery, Refresh, ListCount_Access, ProgrammaticChange, and other methods, but nothing seems to work. None of them fire when the ListCount changes.
How can I get it to enable/disable whenever the ListCount changes?

Jerry