I'm using such library. Perhaps I'm just getting hysterical finding the problem in my codes. This is my last option, to ask from gurus.
My codes is to validate my form, my problem is that it opens in other form, what I want is to catch it by ajax and show it on the same form.

<script type="text/javascript">
		window.addEvent('domready', function(){
	                $('registerForm').addEvent('submit', function(e) {
	                    new Event(e).stop();
	                    var log = $('log_res').empty().addClass('ajax-loading');
	                        update: log,
	                        onComplete: function() {
Here is my html:

<div id="log">
	<div id="log_res">
	<!-- SPANNER -->

<form method= "post" id="registerForm" action = "register.php" >
	<div id = "student_form">
		<p><label for="First_name">First Name</label><input class = "placeholder" type="text" id="First_name" name="First_name"  placeholder= "First Name" required /></p>
		<p><label for="Last_name">Last  Name</label><input class = "placeholder" type="text" id="Last_name" name="Last_name" placeholder="Last name" required/></p>
		<input type="image" name="register" class="submit-btn" src="http://www.roscripts.com/images/btn.gif" alt="submit" title="submit" />