求助，提交PHP界面，这里哪错了？

[wx2016]

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>

<script type="text/javascript">

function ajaxFunction()
 {namex()
 var xmlHttp;
 
 try
    {
   // Firefox, Opera 8.0+, Safari
    xmlHttp=new XMLHttpRequest();
    }
 catch (e)
    {

 // Internet Explorer
   try
      {
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
      }
   catch (e)
      {

     try
         {
         xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
         }
      catch (e)
         {
         alert("您的浏览器不支持AJAX！");
         return false;
         }
      }
    }
 
 
    xmlHttp.onreadystatechange=function()
      {
	   var xx = document.getElementsByName("username")[0].value;
if (xx == ""){
document.getElementById("user_msg").innerHTML='<font color=red>不能为空!</font>';}
else if(document.getElementById('username').value.length < 6){
document.getElementById("user_msg").innerHTML='<font color=red>不能少于六!</font>';
}else if(xmlHttp.readyState==4)
        {
       var x = xmlHttp.responseText;//获取传过来的值
        if(x == 1){
		bb = "1";
		document.getElementById("user_msg").innerHTML='<font color=green>√</font>';
		}else{document.getElementById("user_msg").innerHTML='<font color=red>用户已经被注册</font>';}
		}
      }
 var name=document.myForm.username.value;
 xmlHttp.open("get","<?php echo site_url();?>/user/user_userx/?name="+name,true);//错误跟域名有关系192.168.1.102报错显示没权限 127.0.0.1没报错
    xmlHttp.send(null);
 
 }

</script>



</head>

<body>
<form  name="myForm" action="/index.php/log/registration" method="post" onsubmit="return check();">
登陆账号:<input name="username"     id="username"     onblur="ajaxFunction(name);"    onkeyup="value=value.replace(/[^\w\.\/]/ig,'')"

</form>






</body>
</html>

哪里错了？

xmlHttp.open("get","<?php echo site_url();?>/user/user_userx/?name="+name,true);//错误跟域名有关系192.168.1.102
/user/user_userx/?name="+name,true)这行代码是什么意思？