Ошибка авторизации

public void Autorization_post()
{
    try
    {
        WebRequest webRequest = WebRequest.Create("http://www.wlgame.ru/game.php");
        webRequest.Method = "POST";
        webRequest.Timeout = 120000;
        ((HttpWebRequest)webRequest).UserAgent = "Client Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.2)";
        webRequest.Headers.Add("Accept-Language", "ru-RU,ru;q=0.9,en;q=0.8");
        webRequest.Headers.Add("Accept-Encoding", "gzip, deflate");
        ((HttpWebRequest)webRequest).KeepAlive = true;
        ((HttpWebRequest)webRequest).Referer = "http://wlgame.ru";
        ((HttpWebRequest)webRequest).Accept = "text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/webp, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1";
        webRequest.ContentType = "application/x-www-form-urlencoded";
        byte[] bytes = Encoding.GetEncoding(1251).GetBytes("player_nick=" + Settings.Default.Login + "&player_password=" + Settings.Default.Password);
        webRequest.ContentLength = (long)bytes.Length;
        string additionalHeaders = "Content-Type: application/x-www-form-urlencoded" + Environment.NewLine;
        this.cl.webBrowser.Navigate("http://wlgame.ru/game.php", "", bytes, additionalHeaders);
        this.cl.Log("Авторизация пройдена", true);
    }
    catch (Exception ex)
    {
        this.cl.notifyIcon.ShowBalloonTip(10, string.Empty, "Ошибка авторизации", ToolTipIcon.Error);
        MessageBox.Show("Ошибка авторизации.\n" + ex.Message.ToString(), "Ошибка");
        Application.Exit();
    }
}

public string getRequest(string url)
{
    HttpWebResponse httpWebResponse;
    try
    {
        HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
        httpWebRequest.Headers.Add(HttpRequestHeader.Cookie, this.cl.webBrowser.Document.Cookie);
        httpWebRequest.Referer = "http://wlgame.ru/main.php";
        httpWebRequest.Accept = "*/*";
        httpWebRequest.AutomaticDecompression = (DecompressionMethods.GZip | DecompressionMethods.Deflate);
        httpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.2)";
        httpWebRequest.Headers.Add("Accept-Language", "ru");
        httpWebRequest.Headers.Add("Accept-Encoding", "gzip, deflate");
        httpWebRequest.Headers.Add("UA-CPU", "AMD64");
        httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
    }
    catch
    {
        return string.Empty;
    }
    string result;
    try
    {
        Stream responseStream = httpWebResponse.GetResponseStream();
        using (responseStream)
        {
            using (StreamReader streamReader = new StreamReader(responseStream, Encoding.GetEncoding(httpWebResponse.CharacterSet)))
            {
                result = streamReader.ReadToEnd();
            }
        }
    }
    finally
    {
        if (httpWebResponse != null)
        {
            httpWebResponse.Close();
        }
    }
    return result;
}

GetEncoding(1251)

Default

byte[] sentData = Encoding.Default.GetBytes("login_auth=" + Properties.Settings.Default.Login + "&pass_auth=" + Properties.Settings.Default.Password);