I have problem in internet explorer with ajax open method

function createRequestObject()
{var tmpXmlt;
   if (window.XMLHttpRequest) {
       // Mozilla, Safari would use this method ...
       tmpXmlt = new XMLHttpRequest();
   } else if (window.ActiveXObject) {
      // IE would use this method ...
      try { tmpXmlt= new ActiveXObject("Msxml2.XMLHTTP.6.0"); }
      catch (e1) {}
      try { tmpXmlt=new ActiveXObject("MSXML2.XMLHTTP.3.0"); }
      catch (e2) {}
      try { tmpXmlt= new ActiveXObject("Msxml2.XMLHTTP"); }
      catch (e3) {}
      //Microsoft.XMLHTTP points to Msxml2.XMLHTTP.3.0 and is redundant
     throw new Error("This browser does not support XMLHttpRequest.");
  }
return(tmpXmlt);
}

var xmlhttp = createRequestObject();

function makeGetRequest() {
    xmlhttp.open('get', 'data.xml',false);
    xmlhttp.onreadystatechange = processResponse;
    xmlhttp.send(null);
}