Check if the start date is ealier than the end date 

Verify that the start date is earlier than the end date on the Edit page . Use the following code in the Edit page: Before record updated event.

if toASPDatetime(values("start_date")) > toASPDatetime(values("end_date")) then
  message = "Start date can not be later than End date."
  BeforeEdit = False
else
  BeforeEdit = True
end if

See also:

•About Date Control API

•"Edit as" settings: Date

•AJAX helper object: setMessage()

•Store the date and time when a record is modified