I've searched everywhere but can't find an answer to this problem.
I'm writing a little ajax script but can't get the correct value of the POST request. This is the code so far:
 <textarea id="message" name="message" style="width:100%;"></textarea>
 <input value="SEND" style="border-radius: 5px 5px 5px 5px;" type = 'button' onclick = 'ajaxFunction()'/>
<script type="text/javascript">                             <!--
            //Browser Support Code
            function ajaxFunction(){
               var ajaxRequest;  // The variable that makes Ajax possible!
               try {
                  // Opera 8.0+, Firefox, Safari
                  ajaxRequest = new XMLHttpRequest();
               }catch (e) {
                  // Internet Explorer Browsers
                  try {
                     ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
                  }catch (e) {
                     try{
                        ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
                     }catch (e){
                        // Something went wrong
                        alert("Your browser broke!");
                        return false;
                     }
                  }
               }
               // Create a function that will receive data 
               // sent from the server and will update
               // div section in the same page.
               ajaxRequest.onreadystatechange = function(){
                  if(ajaxRequest.readyState == 4){
                     var ajaxDisplay = document.getElementById('chbox');
                     ajaxDisplay.innerHTML = ajaxRequest.responseText;
                  }
               }
               // Now get the value from user and pass it to
               // server script.
               var message = document.getElementById('message').value;
               var queryString = message ;
               ajaxRequest.open("POST", 'chatdata.php', true);
               //ajaxRequest.send(null); 
               ajaxRequest.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
               ajaxRequest.send('queryString');
            }
</script>
<?php
$message1 = $_REQUEST['message'];
echo $message;
?>
when i use print_r($message); to see the content of the POST value
this is what i get Array ( [queryString] => ). It has no values.
What could be wrong with my code? 
(I would have used jQuery but i'm not well grounded in it yet.)
 
     
     
    