combo dropdown empty

I have a Customer Select form consisting of one unbound combobox control. The user is intended to enter a customer name helped by the dropdown. When the control is entered, and the user starts typing a name, the control should show the first occurance that start with those letters, and the dropdown should show that and the ones that follow (the source is a query in alpha order). I've used this in several other instances with no problem, and thought I'd copied everything from a working instance.

In this instance the control itself acts correctly, following the typing of the user and the dropdown occurs, BUT it is EMPTY.

This is an mbd started originally in 2003 but running in 2010.
The form RecordSource is qryCustomer; popup=No; modal=No; single form.
The combobox ControlSource=blank; format=blank; columncount=1; listrows=16; grow=no; shrink=no; displaywhen=always; RowSource= SELECT DISTINCT [qryCustomer].[FullName] FROM [qryCustomer]; type=Table/Query; boundcolumn=1; limittolist=yes; allowvaluelistedits=no; inheritvaluelist=no; showonlyrowsource=no; enabled=yes; locked=no; autoexpand=yes.
The AfterUpdate property will call a routine to use the name selected.
Since this is working in other instances, can anyone spot what I've screwed up?
Pete