错误代码401未经授权

Question

我收到错误代码401 Unauthorized

我已使用此代码格式：

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(EncodeSlugHeader(listurl));
    request.Method = "GET";
    request.Headers.Add("Authorization", "OAuth " + access_token);
    request.Headers.Add("GData-Version", "2");
    //both Headers.Add and Headers.Set still have Error

这是对的吗？因为我玩https://developers.google.com/oauthplayground/作为参考和它的工作，现在我现在正在将它实现到C＃，我得到了回应401 Unauthorized。

request.Headers.Set("Authorization", "OAuth " + access_token);// ----> reference from https://developers.google.com/oauthplayground/