ajax scrip working on IE but not on mozila fire fox

[sunil.23143]

ajax scrip working on IE but not on mozila fire fox....the script is given below...what can be the posible solutions.....

<script type="text/javascript">
var xmlHttp

function showUser(str)
{ 
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
}
var url="http://merchant06.com/index.php"
alert (url)
url=url+"?q="+str
alert (url)

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;
}

</script>

[rhodesa]

works fine for me in FF3. the only problem i foresee is a cross-domain issue. i see you are trying to load a page from http://merchant06.com/index.php. Is this the same domain as the page calling it? If not, FF won't allow that. If so, remove the domain and just use /index.php:

var url="/index.php"