Ajax xmlHTTPRequest

I'm trying to get the content of a page with AJAX and I get no result..

this is the code:

<script type="text/javascript">
function onSumResponse() {
var xmlhttp;
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","http://www.arihav.com/",true);
xmlhttp.send();
}

</script>

And this is the div in the body:

<div id="myDiv"><h2>Let AJAX change this text</h2></div>
<button type="button" onclick="onSumResponse()">Change Content</button>

What I get after the click is blank div.

EDIT: This code was taken from w3schools

EDIT 2 : This is the code in vbscript that works:

GotothisURL = "http://www.arihav.com"
Set GetConnection = CreateObject("Microsoft.XMLHTTP")
GetConnection.Open "get", GotothisURL, False
GetConnection.Send
ResponsePage = GetConnection.responseText

AJAX does not allowed to access a different server due to origin policy if you want to request another host better use curl or JSON