Display Confirmation MessageBox, but only if certain data entered in form

[bay_dar]

I have an ASP.NET application with vb that I would like to use a
confirmation box with, but only if certain conditions are met. In my
case I would only want this msgbox to show up if a user entered a start
and end range in a form, where the difference between the ranges is
greater then 10. Only the start point is required, so no confirmation
box is required if the ending point is not entered either.

I downloaded a nice confirmation control from here:
http://www.timstall.com/Code/ConfirmButton.aspx

However, it is an all or nothing approach, the confirmation button
always shows up when the form button is submitted. Any ideas on how my
situation could be handled?

Thanks,