通过POST请求提交CSV - POST通过空(c#)

我正试图从文件中读取CSV并通过POST请求提交。由于某些原因，请求中没有发送数据。有人能看到我的代码出了什么问题吗?

    FileStream rdr = new FileStream(path, FileMode.Open, FileAccess.Read);
    byte[] inData = new byte[rdr.Length];
    rdr.Read(inData, 0, Convert.ToInt32(rdr.Length));
    HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
    req.KeepAlive = false;
    req.ContentType = GetContentType(path);
    req.Method = "POST"; 
    req.ContentLength = rdr.Length;
    req.AllowWriteStreamBuffering = true;
    Stream reqStream = req.GetRequestStream();
    reqStream.Write(inData, 0, Convert.ToInt32(rdr.Length));
    Stream dataStream = req.GetResponse().GetResponseStream();
    StreamReader reader = new StreamReader(dataStream);
    responseFromServer = responseFromServer + reader.ReadToEnd();
    rdr.Close();
    reqStream.Close();