Using preventDefault but jQuery ajax POST Still Returns Canceled

Using preventDefault but jQuery ajax POST Still Returns Canceled

why is my post is being cancelled in the network tab of chrome when i
enter some data into the textbox and click sign up? I've even put in
preventDefault() but that doesn't seem to do anything.
<input autofocus style="width: 200pt" type="text" id="email"
placeholder="Enter your Email" />
<input type="submit" value="Sign up" id="submit" class="button green" />
$('#submit').click(function(event) {
event.preventDefault();
var email = $('#email').val();
$.ajax({
type: "POST",
url: "<?=base_url()?>index.php/welcome/register",
data: {email: email},
cache: false,
success: function(data) {
if(data.success === true) {
alert('You have successfully registered.');
}
}
});
});