求助，提交PHP界面，这里哪错了？

<!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>