在线等，急。。。。请各位大哥帮忙，，，急,快要下岗了

在线聊天，

a.asp :

onLoad="makeRequest("9.asp")"


<div id="show"> </div>

ajax实现不刷屏的前提下实现页面定时刷


function makeRequest(url) {
http_request = false;
if (window.XMLHttpRequest) {
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType){
http_request.overrideMimeType(text/xml);
} 
} else if (window.ActiveXObject) {
try{
http_request = new ActiveXObject("Msxml2.XMLHTTP"); 
} catch (e) {
try {
http_request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
}
}
} 
if (!http_request) {
alert("您的浏览器不支持当前操作，请使用 IE 5.0 以上版本!");
return false;
}


//定义页面调用的方法init,不是init();没有();
http_request.onreadystatechange = init; 
http_request.open("GET", url, true);  

//禁止IE缓存
http_request.setRequestHeader("If-Modified-Since","0"); 

//发送数据
http_request.send(null);

//每60秒刷新一次页面
setTimeout("makeRequest("+url+")", 10000); 
}

function timer( fun_name )
{
  window.setInterval( fun_name+"();" , 1500 )
}

function init() { 
if (http_request.readyState == 4) {
if (http_request.status == 0 || http_request.status == 200) {
var msg_str = http_request.responseText;
if(msg_str==""){
msg_str = "";
}
document.getElementById ("show").innerHTML=""+msg_str; 
} else {//http_request.status != 200
alert("!");
}
}
}

<%


  sql22="select top 12 * from music1 order by postid desc"

  set rs22=server.createobject("adodb.recordset")

  rs22.open sql22,conn,1,1
   
  dim msg_str
do while not rs22.eof 
  msg_str=msg_str & "'" & rs22( "content" ) & "'"
  rs22.movenext
  loop
   

%>

ajax实现不刷屏的前提下实现页面定时刷,就是在a.asp显示不了。。。而而没刷新，，，
请各位高手帮我改一下，我是初学者，，快下岗，，