AJAX script not working...

This is my script:

function Handler(Button,Msg)
 {
  var FormData = "";
  if (Msg)
   {
    var DoIt=confirm(Msg)
    if (DoIt==true)
     {
       try {xmlhttp = window.XMLHttpRequest?new XMLHttpRequest(): new ActiveXObject("Microsoft.XMLHTTP");}  catch (e) { alert("Error: Could not load page.");}
      Column = 0
      while (Column <= Columns)
       {
        switch (document.getElementById(Title[Column]).tagName)
         {
           case "DIV":
            if (document.getElementById(Title[Column]).innerHTML>"")
             {
               FormData = FormData + "Entry["+Column+"]=" + escape(document.getElementById(Title[Column]).innerHTML) + "&";
	}
          break;
          case "INPUT":
          if (document.getElementById(Title[Column]).value>"")
           {
             FormData = FormData + "Entry["+Column+"]=" +  escape(document.getElementById(Title[Column]).value) + "&";
            }
          break;
          case "TEXTAREA":
          if (document.getElementById(Title[Column]).innerHTML>"")
           {
             FormData = FormData + "Entry["+Column+"]=" +  escape(document.getElementById(Title[Column]).innerHTML) + "&";
           }
          break;
         }
        Column = Column + 1;
       }
      FormData = FormData + "Button=" + Button + "&Sender=" + document.getElementById("Sender").value;
      xmlhttp.onreadystatechange = function()
      {
        if (xmlhttp.readyState == 4)
         {
           alert(xmlhttp.responseText);
         }
       }
      alert(FormData)
      xmlhttp.open("POST","Handler.php?"+FormData,true);
      xmlhttp.send(null);
      return false;
     }
  }
 }

Code (markup):

The alert confirms the string is correct, however server side post data is missing!?!

Here is my handler code:

<?php
require_once('../Connections/Hawks.php');
mysql_select_db($database_Hawks, $Hawks);
var_dump($_POST['Entry']);
switch ($_POST['Button'])
 {
  case "Save":
   $SQL="Show Columns From ".$_POST['Sender'];
   $ColumnTitles = mysql_query($SQL) or die("Could not connect Column Titles: " . mysql_error());
   while ($Title = mysql_fetch_assoc($ColumnTitles))
    {
     $i++;
     $SQL = "Update ".$_POST['Sender']." Set ".$Title[Field]."='".$_POST['Entry'][$i]."' Where ".$_POST['Sender']."ID = ".$_POST['Entry'][0];
     mysql_query($SQL);
    }
   break;
  case "Delete":
   $SQL = "";
   break;
 }
?>

PHP:

The page is responding...

Can anyone spot the problem?

 

To send the params via POST use something like:

xmlhttp.open("POST","Handler.php",true);

xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.setRequestHeader("Content-length", FormData.length);
xmlhttp.setRequestHeader("Connection", "close");
xmlhttp.send(FormData);

Code (markup):

source:
http://www.openjs.com/articles/ajax_xmlhttp_using_post.php

 

sending the data through the querystring (like your script is doing), would use xmlhttp.open("GET"....etc..