.net 在azure api中注册外部

我试图在azure web api中注册外部，但它显示错误 对象：

{消息：“此请求的授权已被拒绝。”}

我使用的代码如下：

string realm = "api";
HttpRequestMessage request = new HttpRequestMessage();
request.RequestUri = new Uri("https://api-extranet-physmodo.azurewebsites.net/api/Account/RegisterExternal");
request.Method = HttpMethod.Post;
HttpClient client = new HttpClient();
AuthToken.connectHTTP();
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", AuthToken.PhysmodoToken.access_token.ToString());
HttpResponseMessage response = await client.PostAsync(request.RequestUri, content);
response.Headers.WwwAuthenticate.Add(new AuthenticationHeaderValue("Basic", "realm=\"" + realm + "\""));
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
return await response.Content.ReadAsStringAsync();

如何在此api中注册外部