ajax请求问题

每隔2秒发送2个ajax请求，目的是局部刷新两个图，代码如下
JScript code

function getJFreeCharName(){
   if(xmlhttp){
      var url="getCharName";
      var param="tag=1";
      xmlhttp.open("POST",url,true);
      xmlhttp.setRequestHeader("Content-Length",param.length);
      xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
      xmlhttp.onreadystatechange=callBackFun;
      xmlhttp.send(param);
    } 
 }
//处理getJFreeCharName回调结果
function callBackFun(){
   if(xmlhttp.readyState==4){
     if(xmlhttp.status==200){
       setTimeout("getJFreeCharName()",2000);
       document.getElementById("imgs").style.display="";
       document.getElementById("imgs").src=document.getElementById("hidText").value + xmlhttp.responseText;
      }
   }
}
function getJFreeCharName2(){
   if(xmlhttp){
      var url="getCharName";
      var param="tag=2";
      xmlhttp.open("POST",url,true);
      xmlhttp.setRequestHeader("Content-Length",param.length);
      xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
      xmlhttp.onreadystatechange=callBackFun;
      xmlhttp.send(param);
    } 
 }
//处理getJFreeCharName2回调结果
function callBackFun2(){
   if(xmlhttp.readyState==4){
     if(xmlhttp.status==200){
       setTimeout("getJFreeCharName2()",2000);
       document.getElementById("imgs2").style.display="";
       document.getElementById("imgs2").src=document.getElementById("hidText2").value + xmlhttp.responseText;
      }
   }
}
getJFreeCharName();
getJFreeCharName2();

运行后发现只有getJFreeCharName2起作用，getJFreeCharName根本没有起作用，如何修改上面的代码才能让这两个都运行呢？
谢谢！

function getJFreeCharName2(){
  if(xmlhttp){
  var url="getCharName";
  var param="tag=2";
  xmlhttp.open("POST",url,true);
  xmlhttp.setRequestHeader("Content-Length",param.length);
  xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
  xmlhttp.onreadystatechange=callBackFun2;
  xmlhttp.send(param);
  } 
 }