I just asked this question last Friday (1/23/15) the ID# is 28602869 (the title is "How to block date field enter back date"). I got the answer from Rey Obrero but still have one ore question.
The code is doing what I need on the date field but the only problem I notice this morning was if user(s) enter the back date and they want to exit out the form (I have a Cancel button on the form for user(s), normally user users can click Cancel to undo everything), the message still showing unless they removed the date, is anyway that when user(s) click the Cancel button on the form, the message will not show. I did try to put :
if me.text1< Date() then
msgbox "Cannot enter back date!"
text1 = ""
but I got error message.