Please attach a copy of the page instead of cutting and pasting... it is much more difficult for me to debug when I can't open it in Dreamweaver.
It looks like your form action may post to a different page... if so, the the validation would have to be on that page and not this one. Most likely you can move the server validation code to the forgot_password_send.php page and specify the failed redirect to go back to this page and that would make it work properly.