List box populate based on combo box

I have a combo box that is based on a table. The three fields that are
selected should generate a listbox based on a query. The query filters the
the selection.

I can't get any info in the list box. The query works and the listbox
contains the column names but no records.

Am I not using the right fields for the query or not doing a refresh?? I am
lost - been at this for several hours - read all the posts - I know it should
be simple.

Thanks