@jimbill:
Could you please upload a project, as simple as possible, which demonstrates the problem. For example, one form which has ZConnection, ZQuery, DBDateTimePicker, Label and a Button with event which shows the problem. In code, you may add comments that describes what is done and what is expected.
Also, you should provide a "create sql" for a simple db table on which the Query is connected. For example:
create table test (id int, date1 datetime)
Tell us also which db system (Firebird, Postgresql, MySQL, sqlite...) you use. Probably it dosn't matter, but just to be complete.
Zoran
EDIT: You do not need to do this if my next post describes well your problem.