ajax问题。在线等！！！！！

[code=JScript]
var   xmlHttp;
function   S_xmlhttprequest()   {
                  if(window.ActiveXObject)   {
xmlHttp   =   new   ActiveXObject( 'Microsoft.XMLHTTP ');
}   else   if
                      (window.XMLHttpRequest)   {
    xmlHttp   =   new   XMLHttpRequest();
}
}
function   test(id){
S_xmlhttprequest();
var   teti= "tet "+id;;
document.getElementById(teti).style.display= "block ";

//var   us= "query/ajax.php?f_id= "+id;
//alert   (us);
xmlHttp.open( "GET ", "query/ajax.php?f_id= "+id,true);
xmlHttp.onreadystatechange   =   byphp(teti);
xmlHttp.send(null);


}
function   byphp(div)   {

if(xmlHttp.readyState   ==   1)   {
  document.getElementById(div).innerHTML   =   "loading.... ";
}

if(xmlHttp.readyState   ==   4   ){
if(xmlHttp.status   ==   200)   {
    var   loads   =     xmlHttp.responseText;
    document.getElementById(div).innerHTML   =   loads   ;
}
}

}
[/code]

问题！状态一直停留在
if(xmlHttp.readyState == 1) { 
  document.getElementById(div).innerHTML = "loading.... "; 
}

xmlHttp.onreadystatechange = byphp;