i am trying to send xml file using rest service but getting an error The remote server returned an error: (406) Not Acceptable

public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

        request.KeepAlive = false;
        request.ProtocolVersion = HttpVersion.Version10;
        request.ContentType = "application/xml";
        request.Method = "POST";

        StringBuilder sb = new StringBuilder();
        using (StreamReader sr = new StreamReader(xmlFilepath))
        {
            String line;
            while ((line = sr.ReadLine()) != null)
            {
                sb.AppendLine(line);
            }
            byte[] postBytes = Encoding.UTF8.GetBytes(sb.ToString());

            if (timeout < 0)
            {
                request.ReadWriteTimeout = timeout;
                request.Timeout = timeout;
            }

            request.ContentLength = postBytes.Length;

            try
            {
                Stream requestStream = request.GetRequestStream();

                requestStream.Write(postBytes, 0, postBytes.Length);
                requestStream.Close();


                using (var response = (HttpWebResponse)request.GetResponse())
                {
                    return response.ToString();
                }

            }
            catch (Exception ex)
            {
                //msg(ex.Message);
                request.Abort();
                return string.Empty;
            }
        }