cookie判断用户是否登录问题

登录时已经写入cookie的值
Response.Cookies(CookieName)("UserName") = CodeCookie(rs("UserName"))  用户名
Response.Cookies(CookieName)("Vid") = rs("UserID")  用户id
Response.Cookies(CookieName)("UserHashKey") = HashKey  随机密码
<%
'判断用户是否登陆
Dim tempUserID,tempHashKey,tempUserName
Dim UserID,UserName,UserHashKey
    tempUserID=trim(Request.Cookies(CookieName)("Vid"))  能够取出
    tempHashKey=CheckStr(Request.Cookies(CookieName)("UserHashKey")) 能够取出
    tempUserName=CheckStr(DecodeCookie(Request.Cookies(CookieName)("UserName"))) 能够取出
If tempUserName<>""  And tempHashKey<>"" And tempUserID<>"" Then
Set rs=server.CreateObject("adodb.recordset")
sql="select UserHashKey from User where UserID='"&tempUserID&"' and UserName='"&tempUserName&"'"
    rs.open sql,conn,1,1
            if not rs.eof then
            UserHashKey=rs(0)
        rs.close
    set rs=Nothing
        If UserHashKey=tempHashKey Then
        UserID=tempUserID
        UserName=tempUserName
        Else
        UserID=""
        UserName=""
        End If
End If
End If
 %>
问题是：
无论是否登录，UserID UserName的值都无法判断，请问这是怎么回事，是否查询语句有问题？