C＃google驱动器服务帐户下载问题

我创建了服务帐户，我向这个帐户公开了几个文件，一旦我想下载文件，就会抛出exception

Google.Apis.Requests.RequestError错误请求[400]错误[消息[错误请求]位置[ – ]原因[badRequest]域[全局]]

var certificate = new X509Certificate2("*******.p12", "notasecret", X509KeyStorageFlags.Exportable); try { ServiceAccountCredential credential = new ServiceAccountCredential( new ServiceAccountCredential.Initializer("*******..com") { Scopes = scopes }.FromCertificate(certificate)); // Create the service. DriveService service = new DriveService(new BaseClientService.Initializer() { HttpClientInitializer = credential, ApplicationName = "Daimto Drive API Sample", }); var files = service.Files.List().Execute().Files; var request = service.Files.Get(files.First().Id); var stream = new System.IO.MemoryStream(); request.MediaDownloader.ProgressChanged += (IDownloadProgress progress) => { switch (progress.Status) { case DownloadStatus.Downloading: { Console.WriteLine(progress.BytesDownloaded); break; } case DownloadStatus.Completed: { Console.WriteLine("Download complete."); break; } case DownloadStatus.Failed: { Console.WriteLine("Download failed."); break; } } }; request.Download(stream);