Javascript not passing variable to PHP with HTML form

I have contact form, that uses Javascript and PHP.

My problem is that the javascript does not pass its variables to the PHP script. I have discovered the following:

The variables does get set in the javascript, as it passes the variable check inside the javascript and by using alerts showing the variable.

As it travels to the PHP script, the variables are no longer there. I have tried to comment out the check in the PHP script, then it succesfully send a mail, but the mail was empty apart from the static content from the PHP script.

I have tried various different methods, including passing the variables directly from the http.send() function.

Here is the relevant code (These are all 3 different files on the web server):

HTML:

div class="contact_form">
            <h4>Get in touch</h4>
            <form method="post">
                <input type="text" name="Name" id="name" value="Name" onfocus="this.value = this.value=='Name'?'':this.value;" onblur="this.value = this.value==''?'Name':this.value;" />
                <input type="text" name="Email" id="email" value="Email" onfocus="this.value = this.value=='Email'?'':this.value;" onblur="this.value = this.value==''?'Email':this.value;" />
                <input type="text" value="Subject (Hosting, Requests, Appeal, Report, etc.)" id="subject" onfocus="this.value = this.value=='Subject (Hosting, Requests, Appeal, Report, etc.)'?'':this.value;" onblur="this.value = this.value==''?'Subject (Hosting, Requests, Appeal, Report, etc.)':this.value;" />
                <textarea name="Message" id="body" onfocus="this.value = this.value=='Message'?'':this.value;" onblur="this.value = this.value==''?'Message':this.value;">Message</textarea>
                <input type="submit" name="submit" id="submit" value="send" class="submit-button" onClick="return check_values();" />
            </form>
            <div id="confirmation" style="display:none; position: relative; z-index: 600; font-family: 'Open Sans', sans-serif; font-weight: 300; font-size: 16px; color: #4e4e4e;"></div>
        </div> <!-- end .contact_form -->

Javascript:

var http = createRequestObject();
var areal = Math.random() + "";
var real = areal.substring(2,6);

function createRequestObject() {
    var xmlhttp;
    try { xmlhttp=new ActiveXObject("Msxml2.XMLHTTP"); }
  catch(e) {
    try { xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");}
    catch(f) { xmlhttp=null; }
  }
  if(!xmlhttp&&typeof XMLHttpRequest!="undefined") {
    xmlhttp=new XMLHttpRequest();
  }
    return  xmlhttp;
}

function sendRequest() {
    var rnd = Math.random();
    var name = escape(document.getElementById("name").value);
    var email = escape(document.getElementById("email").value);
    var subject = escape(document.getElementById("subject").value);
    var body = escape(document.getElementById("body").value);

    try{
        http.open('POST','pform.php');
        http.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        http.send('name='+name+'&email='+email+'&subject='+subject+'&body='+body+'&rnd='+rnd);
        http.onreadystatechange = handleResponse;
    }
    catch(e){}
    finally{}
}

function check_values() {
    var valid = '';

    var name = document.getElementById("name").value;
    var email = document.getElementById("email").value;
    var subject = document.getElementById("subject").value;
    var body = document.getElementById("body").value;
    if(trim(name) == "" ||
        trim(email) == "" ||
        trim(subject) == "" ||
        trim(body) == "") {
            alert("Please complete all fields");
    } else {
        if(isEmail(email)) {
            document.getElementById("submit").disabled=true;
            document.getElementById("submit").value='Please Wait..';
            sendRequest();
        } else {
            alert("Email appears to be invalid\nPlease check and try again");
            document.getElementById("email").focus();
            document.getElementById("email").select();
        }
    }
}

function handleResponse() {
    try{
    if((http.readyState == 4)&&(http.status == 200)){
        var response = http.responseText;
      document.getElementById("confirmation").innerHTML = response;
      document.getElementById("confirmation").style.display ="";
        }
  }
    catch(e){}
    finally{}
}

function isUndefined(a) {
   return typeof a == 'undefined';
}

function trim(a) {
    return a.replace(/^s*(S*(s+S+)*)s*$/, "$1");
}

function isEmail(a) {
   return (a.indexOf(".") > 0) && (a.indexOf("@") > 0);
}

PHP:

<?php
error_reporting(0);

$page_title = "Contact Us Form";
$email_it_to = "[email protected]";
$error_message = "Please complete the form first";
$confirmation = "Thank you, your message has been successfully sent.";

if(!isset($rnd) || !isset($name) || !isset($email) || !isset($subject) || !isset($body)) {
    echo $error_message;
    die();
}

    $email_from = $email;
    $email_subject = "Contact Form: ".stripslashes($subject);
    $email_message = "Please find below a message submitted by '".stripslashes($name);
    $email_message .="' on ".date("d/m/Y")." at ".date("H:i")."\n\n";
    $email_message .= stripslashes($body);

    $headers = 'From: '.$email_from."\r\n" .
   'Reply-To: '.$email_from."\r\n" .
   'X-Mailer: PHP/' . phpversion();

    mail($email_it_to, $email_subject, $email_message, $headers);

    echo "<b>$confirmation</b>";
    die();
?>