Problems with POST request parameters in C#

This website uses POST to send data whenever the user clicks on a calendar to change the date. I used Firebug to inspect it. The target URL is this. The post data (space-separated) for a particular example is LeagueID=9 GameDate=4-29-2011 Season=2010-2011 Refresh=false LastUpdateTime=01-01-1900 type=Matchups RefreshStartTime=15-5-2011-1308094688683 Week= conferenceID=.

And here are the headers:

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

I'd like to make that POST request using WebRequest (or whetever else does the trick). Here开发者_StackOverflow社区's my attempt:

        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();

But it doesn't work. The response code is OK, but the response itself is this:

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)

What's the deal? I can see that something's wrong with the params since the content length of the request is 175 (as opposed to the 169 from the request made by Firefox).

Why not use NameValueCollection to POST your parameters using a WebClient? It does the tricky stuff for you. The code at the bottom of the linked page is about as simple as it comes. Unlike the sample, you should probably deal thoughtfully with disposal of the WebClient.

Don't ASCII encode when you specify UTF-8 later. Make sure to url encode parameters. Try changing the content-type to 'x-www-form-urlencoded'.