<div class="alert alert-danger" id="errorBox" style="display:none; padding:15px;">
</div>

<script type="text/javascript">
        $(document).ready(function () {
            $('#signIn').submit(function (e) {
                if ($('#tbxUsername').val().length == 0) {
                    $('#errorBox').html('<strong>Error:</strong> You need to enter your username!');
                    $('#errorBox').hide().show('shake');
                    return false;
                } else if ($('#tbxPassword').val().length == 0) {
                    $('#errorBox').html('<strong>Error:</strong> You need to enter your password!');
                    $('#errorBox').hide().show('shake');
                    return false;
                }
            });
        });
    </script>