AJAX not working in Firefox

I have an ASP program that uses AJAX. Everything is working fine but, when I submit all the information, the value that a COMBOBOX get from AJAX isnt passing to the next form in FireFox. :eek: If I use IE, everything works fine.

If you guys can please check my code, i would be glad. :)

This is the show_city.js that im importing in an ASP file.

Code:

---

var xmlHttp

function MandaID(str)
{
        xmlHttp=GetXmlHttpObject()
        if (xmlHttp==null)
        {
        alert ("This browser does not support HTTP Request")
        return
        }

        var url="select_city.asp"
        url=url+"?state_cod="+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("show_city").innerHTML=xmlHttp.responseText
        }
}

function GetXmlHttpObject()
{
        var objXMLHttp=null
       
        if (window.XMLHttpRequest)
        {
        objXMLHttp=new XMLHttpRequest()
        }
        else if (window.ActiveXObject)
        {
        objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
        }
        return objXMLHttp

}

---