incorporating query parameter values right in the Form

[Lee Harwell]

In a report I can display the search criteria used in a
query by the following means:

set the textbox control's Control Source property to the
following expression:
="Orders taken between " & [Enter a start date] &
" and " & [Enter an end date]

I want this same functionality in my Form header.
However, the above does not seem to work. What must I do
in order for my query search criteria to appear in a text
box in my FORMS?