PHP: Echoing values of input fields
===

I am grabing the values of several input fields with the help of an Ajax/JS function. THe issue is that the values of the textbox are not being echoed. I checked with firebug tool and it shows that the post is performed but there is blank value. Why is the php not echoing the value when the js function submits it?

[EXAMPLE][1]

**JS**

    <script>
    $(document).ready(function() { 
        var timer = null;  
        var dataString;    
        function submitForm(){ 
            $.ajax({ type: "POST", 
                url: "index.php", 
                dataType: 'json', 
                success: function(result){ 
                $('#special').html('<p>' +  $('#resultval', result).html() + '</p>');} 
                                  }); 
            return false; 
        } 
        $('#contact_form').on('keyup', function() { 
            clearTimeout(timer); 
            timer = setTimeout(submitForm, 2000); 
        }); 
    });  
    </script>


**HTML**

    <form action="" method="post" enctype="multipart/form-data" id="contact_form" name="form4"> 
     <div class="row">  
      <div class="label">Contact Name *</div> <!-- end .label --> 
        <div class="input"> 
          <input type="text" id="contact_name" class="detail" name="contact_name" value="<?php echo isset($_POST['contact_name'])? $_POST['contact_name'] : ''; ?>" />  
          <div id="special"><span id="resultval"><? echo $_POST['contact_name'];  ?></span></div> 
        </div><!-- end .input--> 
     </div><!-- end .row --> 
     
     <div class="row">  
      <div class="label">Email Address *</div> <!-- end .label --> 
       <div class="input"> 
        <input type="text" id="email" class="detail" name="email" value="<?php echo isset($_POST['email'])? $_POST['email'] : ''; ?>" />  
        <div id="special"><span id="resultval"><? echo $_POST['email'];  ?></span></div> 
       </div><!-- end .input--> 
     </div><!-- end .row --> 
    </form>


  [1]: http://webprolearner2346.zxq.net/TabsNextPrev/index.php