Cannot get IE to make xmlhttp

[Greaser9780]

I have tried dozens of mehtods for this. I run an alert to describe the xmlhttp. In firefox it returns  "object xmlhttprequest" in IE all I get is "object". The odd part is that I get no errors. I checked all of my browser settings and everything is ok. I even updated to IE7 which should show it just as FF but it doesn't. The following is my .js file:

var xmlHttp


function showUser(str)
{ 
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
} 
alert(xmlHttp);
var url="showUser.php"
url=url+"?q="+str
url=url+"&sid="+Math.random()
xmlHttp.onreadystatechange=stateChanged 
xmlHttp.open("GET",url,true)
xmlHttp.send(null)
}

function stateChanged() 
{ 
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{ 
document.getElementById("txtHint").innerHTML=xmlHttp.responseText 
} 
}

  
function GetXmlHttpObject()
{
var xmlHttp=null;
try
{
// Firefox, Opera 8.0+, Safari
xmlHttp=new XMLHttpRequest();
}
catch (e)
{
//Internet Explorer
try
  {
  xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
  }
catch (e)
  {
  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
}
return xmlHttp;
}

 

This is supposed to bring up another dropdown box with the info from the first one. It only brings up the dropdown box with empty options. IT's like it creates an object but isn't passing all the info. showUser is the function that set the var q. It gets added where it says url="?q="+str  str is the value of the first dropdown. I just can't figure out why this doesn't work in IE but it does everywhere else even netscape. I even have the added number to stop the cache issue.