PHP Ajax函数在Win 2003机器中不起作用

我用javascript（for php）编写了一个ajax函数。它在WIN-XP机器中运行良好，但在WIN-2003中不起作用。

对于onclick事件，我正在调用fun_LeaveLength_JS_G函数。在里面，我正在设置xmlhttp2.onreadystatechange=function（）。这并没有执行。

我的功能如下：

function fun_LeaveLength_JS_G(dG1,dG2)
{
    err2=true;
    G_EmpIdFromJS=document.frmLeaveApp.txtG_EmpId.value;
    G_PL_CountJS=document.frmLeaveApp.txt_PLCount.value;
    PLAvailabe_JS= document.frmLeaveApp.PL_available.value;
    CLAvailabe_JS=document.frmLeaveApp.CL_available.value;
    LWPAvailabe_JS=document.frmLeaveApp.LWP_available.value;
    MLAvailabe_JS=document.frmLeaveApp.ML_available.value;
    COMPAvailabe_JS=document.frmLeaveApp.COMP_available.value;
    FromHomeAvailabe_JS=document.frmLeaveApp.txt4mHome_available.value;
    LeaveType_JS=document.frmLeaveApp.sltLeaveType.value;
    alert(PLAvailabe_JS+" "+ CLAvailabe_JS +" "+ LWPAvailabe_JS +" "+ MLAvailabe_JS +" "+ COMPAvailabe_JS +" "+ FromHomeAvailabe_JS + " "+ LeaveType_JS);
    if (dG1=="" || dG2=="")
    {
      return;
    }
    FromDate_G= dG1;
    ToDate_G=dG2;
    var d = new Date();
    //if(str=="")
    {   
        if (window.XMLHttpRequest)
        {
          xmlhttp2=new XMLHttpRequest();
        }
        else
        {
          xmlhttp2=new ActiveXObject("Microsoft.XMLHTTP");
        }           
        xmlhttp2.onreadystatechange=function()
        {                           
            alert("Before response from the AJAX");
          if (xmlhttp2.readyState==4 && xmlhttp2.status==200)
            {                
               document.frmLeaveApp.txtLeaveLeangth.value=xmlhttp2.responseText;    
               alert("in ajax fileError 2 is "+err2);
                alert("Ajax result is : "+xmlhttp2.responseText);
                //LeaveLength_JS=xmlhttp2.responseText();
                if(xmlhttp2.responseText==1)
                {       
                    err2=true;
                    alert("when ajax result is 1 error 2 is "+err2);
                    LeaveLength_JS=xmlhttp2.responseText();                     
                }                   
                if(xmlhttp2.responseText==0)
                {
                    err2=false;// allow to apply leave
                    alert("when ajax result is 0 error 2 is "+err2);
                }
                else
                {
                    err2=true;
                    alert("when ajax result is other then error 2 is "+err2);
                    Alert("This is developer error. Please Inform to System admin");
                }                                       
            }
        }           
        xmlhttp2.open("GET","http://localhost/MyProject/LeaveLength_Ajax.php?_Get_FromDate="+FromDate_G+"&_Get_ToDate="+ToDate_G+"&PLAvailabe_JS="+PLAvailabe_JS +"&CLAvailabe_JS="+CLAvailabe_JS +"&LWPAvailabe_JS="+LWPAvailabe_JS+"&MLAvailabe_JS="+MLAvailabe_JS+"&COMPAvailabe_JS="+COMPAvailabe_JS+"&FromHomeAvailabe_JS="+FromHomeAvailabe_JS +"&LeaveType_JS="+LeaveType_JS,true);          
        xmlhttp2.send();
    }       
    alert("At the end Error 2 is "+err2);
}

哪里出了问题？我需要包含或安装任何支持软件吗？