得不到IP地址?解决方案

得不到IP地址?
函数如下:
Function   GetRealIP()
      dim   userip
      userip=request.ServerVariables( "HTTP_X_FORWARDED_FOR ")
      if   userip= " "   then   userid=Request.ServerVariables( "REMOVE_ADDR ")
      GetRealIP=userip
End   Function

调用其函数
userip=GetRealIP()

为何userip为空值呢?谢谢

------解决方案--------------------
是Request.ServerVariables( "REMOTE_ADDR ")吧
------解决方案--------------------
Function GetRealIP()
GetRealIP=request.ServerVariables( "HTTP_X_FORWARDED_FOR ")
if GetRealIP= " " then GetRealIP=Request.ServerVariables( "REMOTE_ADDR ")
End Function
conn.execute( "update bbs_users set LastLoginIP= ' "&GetRealIP& " ',LastLoginTime= ' "&now()& " ',LoginTimes=LoginTimes+1 where UserID= "&rs( "UserID "))