求解，大家看看这个代码有没有错误？

<%
If request.Form("submit") = "确认修改" Then
    If request.Form("pf_site_hits") = "" Or Not IsNumeric(request.Form("pf_site_hits")) Then
        Call infoback("访问统计不能为空，而且必须为数字！")
    End If
    Set rs = server.CreateObject("adodb.recordset")
    sql = "select * from pf_site"
    rs.Open sql, conn, 1, 3
    rs("pf_site_name") = request.Form("pf_site_name")
    rs("pf_uploadfile") = request.Form("pf_uploadfile")
    rs("pf_site_contact") = request.Form("pf_site_contact")
    rs("pf_site_tel") = request.Form("pf_site_tel")
    rs("pf_site_mobile") = request.Form("pf_site_mobile")
    rs("pf_site_fax") = request.Form("pf_site_fax")
    rs("pf_site_qq") = request.Form("pf_site_qq")
    rs("pf_site_msn") = request.Form("pf_site_msn")
    rs("pf_site_email") = request.Form("pf_site_email")
    rs("pf_site_url") = request.Form("pf_site_url")
    rs("pf_site_address") = request.Form("pf_site_address")
    rs("pf_site_keywords") = request.Form("pf_site_keywords")
    rs("pf_site_description") = request.Form("pf_site_description")
    rs("pf_site_icp") = request.Form("pf_site_icp")
    rs("pf_site_hits") = request.Form("pf_site_hits")
    rs("pf_site_copyright") = request.Form("pf_site_copyright")
    rs("pf_site_code") = request.Form("pf_site_code")
    rs.update
    Call close_rs
    Call close_conn
    Call infoback("网站信息修改成功！")
End If
%>

初学还不是很懂，我是下载网上的源码，能够进入后台，但是点击修改返回500错误，请教大虾，这段程序有没有错！