C# Youtube API上载-不完整的多部分正文错误

我正试图通过HttpWebRequest在Youtube上传视频。按照API文档中给出的示例进行上传时，一切似乎都很好。 我看到请求的格式正确，发送了内容和令牌，但我收到了不完整的多部分正文作为响应

谢谢布莱林

public bool YouTubeUpload()

{
    string newLine = "\r\n";

    //token and url are retrieved from YouTube at runtime.
    string token = string.Empty;
    string url = string.Empty;

    // construct the command url
    url = url + "?nexturl=http://www.mywebsite.com/";

    // get a unique string to use for the data boundary
    string boundary = Guid.NewGuid().ToString().Replace("-", string.Empty);

    foreach (string file in Request.Files)
    {
        HttpPostedFileBase hpf = Request.Files[file] as HttpPostedFileBase;
        if (hpf.ContentLength == 0)
            continue;

        // get info about the file and open it for reading
        Stream fs = hpf.InputStream;

        HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url);
        webRequest.ContentType = "multipart/form-data; boundary=" + boundary;
        webRequest.Method = "POST";
        webRequest.KeepAlive = true;
        webRequest.Credentials = System.Net.CredentialCache.DefaultCredentials;

        MemoryStream memoryStream = new MemoryStream();
        StreamWriter writer = new StreamWriter(memoryStream);

        //token
        writer.Write("--" + boundary + newLine);
        writer.Write("Content-Disposition: form-data; name=\"{0}\"{1}{2}", "token", newLine, newLine);
        writer.Write(token);
        writer.Write(newLine);

        //Video
        writer.Write("--" + boundary + newLine);
        writer.Write("Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"{2}", "File1", hpf.FileName, newLine);
        writer.Write("Content-Type: {0}" + newLine + newLine, hpf.ContentType);

        writer.Flush();

        byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes(string.Format("--{0}--{1}", boundary, newLine));

        webRequest.ContentLength = memoryStream.Length + fs.Length + boundarybytes.Length;
        Stream webStream = webRequest.GetRequestStream();

        // write the form data to the web stream
        memoryStream.Position = 0;
        byte[] tempBuffer = new byte[memoryStream.Length];
        memoryStream.Read(tempBuffer, 0, tempBuffer.Length);
        memoryStream.Close();
        webStream.Write(tempBuffer, 0, tempBuffer.Length);

        // write the file to the stream
        int size;
        byte[] buf = new byte[1024 * 10];
        do
        {
            size = fs.Read(buf, 0, buf.Length);
            if (size > 0)
                webStream.Write(buf, 0, size);

        } while (size > 0);

        // write the trailer to the stream
        webStream.Write(boundarybytes, 0, boundarybytes.Length);

        webStream.Close();
        fs.Close();

        //fails here. Error - Incomplete multipart body. 
        WebResponse webResponse = webRequest.GetResponse();
    }

    return true;
}