PHP MySQL JQuery表单没有'；t在客户端进行验证

我有一个简单的联系表单，它在提交时发布到MySql，我试图在提交表单之前在客户端进行验证（我将在客户端工作后实现服务器端验证）。出于某种原因，当我提交表单时，它会发布到DB，但不会启动客户端验证。如有任何帮助，我们将不胜感激。

这是HTML（twitter引导程序）代码：

<form action="/contact.php" method="post" id="contactUs">
    <div class="control-group">
       <label class="control-label" for="Name">NAME<sup>*</sup></label>
       <div class="controls">
         <input type="text" class="span4" name="name" placeholder="Name" id="name">
         <span class="help-block"></span> 
        </div>
    </div>
    <div class="control-group">
       <label class="control-label" for="Email">EMAIL<sup>*</sup></label>
       <div class="controls">
         <input type="text" class="span4" name="email" placeholder="Email" id="email">
         <span class="help-block"></span> 
       </div>
    </div>
    <div class="control-group">
       <label class="control-label" for="Subject">Subject<sup>*</sup></label>
       <div class="controls">
         <input type="text" class="span4" name="subject" placeholder="Subject" id="subject">
         <span class="help-block"></span>
       </div>
     </div>
     <div class="control-group">
        <label for="textarea" class="control-label" for="Comment">COMMENTS<sup>*</sup></label>
        <div class="controls">
          <textarea rows="5" class="span6" name="comments" id="message"></textarea>
          <span class="help-block"></span>
        </div>
      </div>
      <div class="control-group form-button-offset">
      <input type="submit" class="btn btn-large btn-primary pull-right" value="Send Message" />
     </div>
      <input type="hidden" name="redirect" value="contact_us.html" />

<script src="js/jquery-1.9.0.min.js"></script>
<script src="js/jquery.validate.min.js"></script>
<script src="js/contactUs.js"></script>
<script src="js/bootstrap.js"></script>
<script src="js/bootstrap.min.js"></script>

以下是contactUs.js:的代码

$(document).ready(function(){
$('#contactUs').validate({
    rules: {
        name: {
            minlength: 4,
            required: true
        },
        email: {
            required: true,
            email: true,
        },
        subject: {
            minlength: 5,
            required: true
        },
        submission_Reason: {
            minlength: 5,
            required: true
        },
        comments: {
            minlength: 8,
            required: true,
        }
    },
    messages: {
        name: "Please enter your first and last name",
        email: "Please enter a valid email address",
        subject: "Please enter a subject",
        comments: "Please enter a short message",
    },
    highlight: function (element, errorClass, validClass) {
        $(element).closest('.control-group').removeClass('success').addClass('error');
    },
    unhighlight: function (element, errorClass, validClass) {
        $(element).closest('.control-group').removeClass('error').addClass('success');
    },
    success: function (label) {
        $(label).closest('form').find('.valid').removeClass("invalid");
    },
    errorPlacement: function (error, element) {
        element.closest('.control-group').find('.help-block').html(error.text());
    }
});
};

和PHP contact.PHP文件：

    <?php
$con=mysqli_connect("host","username","password","dbname");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }
$sql="INSERT INTO contactUs (name, email, subject, comments)
VALUES
('$_POST[name]','$_POST[email]','$_POST[subject]','$_POST[comments]')";
$sql="INSERT INTO contactUs (`date_created`) VALUES (now())";
if (!mysqli_query($con,$sql))
  {
  die('Error: ' . mysqli_error($con));
  }
echo "Your form has been received, Thank you!";
mysqli_close($con);
?>

当我提交表单时，不会触发客户端验证，结果是：

• 表单被提交并发布到DB
• 我明白了：你的表格已经收到了，谢谢

我做错了什么？为什么验证没有发生？