Я пытаюсь получить пользователей Google из моего домена с помощьюgoogle service account.

Но это выдает ошибку

Error:"access_denied", Description:"Requested client not authorized.", Uri:""

Мой код

X509Certificate2 certificate = new X509Certificate2(key_path,
                         "notasecret", X509KeyStorageFlags.Exportable);

ServiceAccountCredential credential = new ServiceAccountCredential(
           new ServiceAccountCredential.Initializer("publickey.gserviceaccount.com")
           {   Scopes = scopes,
               User = "[email protected]"
           }.FromCertificate(certificate));

var service = new DirectoryService(new BaseClientService.Initializer()
        {
            HttpClientInitializer = credential,
            ApplicationName = "appname",
        });

service.Users.List().Domain = "domain.com";
Users results = service.Users.List().Execute();

заранее спасибо