有人碰到过webrequest.timeout设置无效的有关问题吗

有人碰到过webrequest.timeout设置无效的问题吗？

C# code

  protected static string GetHttpData(string url)    {        StreamReader sr = null;        string str = "";        try        {            WebRequest temp = WebRequest.Create(url);            temp.Timeout = 1000;            //读取            WebResponse myTemp = temp.GetResponse();            sr = new StreamReader(myTemp.GetResponseStream(), System.Text.Encoding.GetEncoding("gb2312"));            str = sr.ReadToEnd();        }        catch        {            return "-1";        }        return str;    }