[AccessD] Query fails when using NOT IN ???

All,

This is weird.  I have a query that is supposed to return all records
from a Time Entry table where the Entry ID is not in the Line Item
table.

So basically, it's "SELECT [field list here] FROM TimeEntry WHERE
EntryID NOT IN (SELECT EntryID FROM LineItem)".

Pretty simple, right?  I can verify that there are a ton of records
in TimeEntry that have no corresponding record in LineItem.  But when
I run the query above, it returns no records.

Any idea?

-C-