typeerror 'step up' called on an object that does not implement interface htmlinputelement
<p>I'm doing ajax call when I click one the submit button it shows the error
<code>typeerror 'step up' called on an object that does not implement interface htmlinputelement</code></p>

<p>my ajax code is </p>

<pre><code>$('form#login, form#register').on('submit', function (e) {
    //if (!$(this).valid()) return false;
    $('p.status', this).removeClass('owner-fail');
    $('p.status', this).removeClass('owner-success');
    $('p.status', this).show().text(ajax_auth_object.loadingmessage);
        username =  $('form#login #username').val();
        password = $('form#login #password').val();
        security = $('form#login #security').val();
        email = '';

    if ($(this).attr('id') == 'register') {
        action      = 'ajaxregister';
        username    = $('form#register #username').val();
        contact     = $('form#register #contact').val();
        fname       = $('form#register #fname').val();
        lname       = $('form#register #lname').val();
        email       = $('form#register #email').val();
        security    = $('form#register #signonsecurity').val();
    }  
    ctrl = $(this);
    $.ajax({
        type: 'POST',
        dataType: 'json',
        url: ajax_auth_object.ajaxurl,
        data: {action: action,username: username,fname: fname,lname: lname,password: password,contact: contact,email: email,security: security},
        success: function (data) {
            if(data.loggedin == true || data.loggedin== false )
            $('p.status', ctrl).addClass(data.class);
            $('p.status', ctrl).text(data.message);
            if (data.loggedin == true &amp;&amp; data.success== true) {
                document.location.href = ajax_auth_object.redirecturl;
            }else if(data.loggedin == true)
                $('#register input').val('');
            $('p.status', ctrl).delay(7000).fadeOut(400);

        }
    });
    e.preventDefault();
});
</code></pre>

<p>I am using the same ajax for registration and login, and thing is that its perfectly working for registration and not for login
my url ls that
<a href="http://property.stw-services.com/add-place/" rel="nofollow">http://property.stw-services.com/add-place/</a></p>

<p>The strange is that, first If i once try for register it'll work for register and then try for login then will work perfectly, but after page page load first time i try for login its not working</p>