[求助]asp+ajax 中调用onreadystatechange属性调用的方法出错.类型不匹配: 'onrea

<%
dim xml ,objXMLDOM ,sql
Set objXMLHTTP = Server.CreateObject("Microsoft.XMLHTTP")
objXMLHTTP.onreadystatechange=testt
objXMLHTTP.open "GET","http://localhost:800/yqhl/test.asp",FALSE
objXMLHTTP.send (null)

function testt()
if objXMLHTTP.readyState = 4 then
if objXMLHTTP.status = 200 then
response.Write "success!"
end if
end if
end function
%>
俺用javascript试过了OK但用vbscript是老是提示 :

Microsoft VBScript 运行时错误 错误 '800a000d'

类型不匹配: 'onreadystatechange'

这是怎么回事呢 ?
发了两次贴
请各位大虾赐教了