C＃中的POST请求参数问题

Host    scores.covers.com
User-Agent  Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
Accept  text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language en-gb,en;q=0.5
Accept-Encoding gzip, deflate
Accept-Charset  ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive  115
Connection  keep-alive
Referer http://scores.covers.com/basketball-scores-matchups.aspx
Content-Length  169
Content-Type    text/plain; charset=UTF-8
Cookie  __loooooooooongCookieString

WebRequest

        string parameters = \"LeagueID=\\\"9\\\"&GameDate=\\\"4-29-2011\\\"&Season=\\\"2010-2011\\\"&Refresh=\\\"false\\\"&LastUpdateTime=\\\"01-01-1900\\\"&type=\\\"Matchups\\\"&RefreshStartTime=\\\"15-5-2011-1308094688683\\\"&Week=&conferenceID=\";
        byte[] bytes = Encoding.ASCII.GetBytes(parameters);

        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(\"http://scores.covers.com/ajax/SportsDirect.Controls.LiveScoresControls.Scoreboard,SportsDirect.Controls.LiveScoresControls.ashx?_method=UpdateScoreboard&_session=no\");


        req.Method = \"POST\";
        req.ContentLength = bytes.Length;
        req.ContentType = \"text/plain; charset=UTF-8\";
        Console.WriteLine(req.ContentLength); // 175

        Stream reqStream = req.GetRequestStream();
        reqStream.Write(bytes, 0, bytes.Length);
        reqStream.Close();

        WebResponse resp = req.GetResponse();
        Console.WriteLine(((HttpWebResponse)resp).StatusDescription); // OK

        Stream respStream = resp.GetResponseStream();
        StreamReader reader = new StreamReader(respStream);
        Console.WriteLine(reader.ReadToEnd());
        resp.Close();

new Object();r.error = new ajax_error(\'System.FormatException\',\'Input string was
 not in a correct format.\\r\\nCould not retreive parameters from HTTP request.\',0
)new Object();r.error = new ajax_error(\'System.ArgumentException\',\'Object of typ
e \\\'System.DBNull\\\' cannot be converted to type \\\'System.Int32\\\'.\',0)