小菜鸟求高手指点，asp+access+ajax无刷新检查用户名是否被注册
现在老是提示 网络链接失败 这是怎么回事？
代码如下：
<%@LANGUAGE="VBSCRIPT" codepage="65001"%><!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>用户注册</title><style type="text/css">.regstyle{ margin:15px 0;}label{ margin-right:10px;}</style><script language="javascript" type="text/javascript">var imgok ="<img src='images/regright.png' align='absmiddle' hspace='2'>"var imgwrong="<img src='images/regwrong.png' align='absmiddle' hspace='2'>"function checkmail(){ var xmlhttp; try { xmlhttp=new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) { try { xmlhttp=new XMLHttpRequest(); } catch (e) { } } }var email = document.form1.email.value;var ts = document.getElementById("youjiants");var illegalemail = !(/^[\w\-\_\.u4e00-\u9fa5]+@[\w\-\_u4e00-\u9fa5]+(\.[\w\-\_u4e00-\u9fa5]+)+$/.test(email));if(illegalemail){ ts.innerHTML =" " + imgwrong + "请正确输入您的邮箱"; ts.style.color="#000000";}else{ xmlhttp.open("get","checkuser.asp?email="+escape(email)+ "&t=" + new Date().getTime()); xmlhttp.setRequestHeader("content-type","text/xml"); xmlhttp.setRequestHeader("If-Modified-Since","0"); xmlhttp.onreadystatechange=function() { if(4==xmlhttp.readyState) { if(200==xmlhttp.status) { if (xmlhttp.responseText=="yes") { ts.innerHTML="此用户名已经存在"; } else { ts.innerHTML="输入正确"; } } else { ts.innerHTML="网络链接失败"; } } } xmlhttp.send(null); return false; } }</script></head><body><h2>注册信息</h2><form id="form1" name="form1"><div class="regstyle"><label for="email">邮箱</label><input name="email" id="email" type="text" onBlur="checkmail()" /><span id="youjiants"></span></div></form></div></body></html><!--#include file="Connections/connuser.asp" --><%set rs = Server.CreateObject("adodb.recordset")email=Replace(request.querystring("email"),"'","")sql="select * from user where email='"&email&"'"rs.open sql,conn,1,1if rs.eof then response.write "no"else response.write "yes" end if rs.close %><%//' FileName="Connection_ado_conn_string.htm"//' Type="ADO" //' DesigntimeType="ADO"//' HTTP="true"//' Catalog=""//' Schema=""set rs = Server.CreateObject("adodb.recordset")set conn = Server.CreateObject("ADODB.Connection")Dim MM_connuser_STRINGMM_connuser_STRING = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="&server.Mappath("./djgjeigxigi15980/kdjgiegj128490.mdb")conn.Open MM_connuser_STRING%>
' FileName="Connection_ado_conn_string.htm"' Type="ADO" ' DesigntimeType="ADO"' HTTP="true"' Catalog=""' Schema=""set rs = Server.CreateObject("adodb.recordset")set conn = Server.CreateObject("ADODB.Connection")Dim MM_connuser_STRINGMM_connuser_STRING = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="&server.Mappath("./djgjeigxigi15980/kdjgiegj128490.mdb")conn.Open MM_connuser_STRING