[AccessD] Stupid DateTime/Calendar Picker Question

Ok....Here's the scenario.  I have a report that I
need to run.  It has a start date and time and a stop
date and time, obviously.  The back-end database has
the start and end times in DateTime format, I cannot
deviate from this format in the backend.

I have a calendar picker to select start date and one
to select stop date.  I have a time picker to select
the start time and stop time.  I have four text boxes
that take the resultant dates and times from the
ActiveX controls, so I can use them.  From there I
have two text boxes that convert them to pseudo
DateTime start and stop times thusly "=[start_date] &
" " & [start_time]" and "=[end_date] & " " &
[end_time]".  The resultant formats LOOK correctly
formatted for the DateTime field.  I.e. they look like
9/19/2003 5:00:00 AM.  HOWEVER they don't seem to work
properly against the ACTUAL DateTime fields in my
back-end database when I use a Between statement.

What am I doing wrong?  Thank you in advance for your assistance.