无法找到“自动发现服务”：Exchange

Question

ExchangeService Service = new ExchangeService(ExchangeVersion.Exchange2007_SP1);
Service.Credentials = new WebCredentials("abc", "123456", "mydomain.net");
Service.TraceEnabled = true;
Service.UseDefaultCredentials = false;
Service.EnableScpLookup = false;
Service.AutodiscoverUrl("abc@mydomain.net");
Folder inbox = Folder.Bind(Service, WellKnownFolderName.Inbox);
Console.WriteLine("The folder name is " + inbox.DisplayName.ToString());

我正在尝试通过交换登录，保留“无法找到自动发现服务”的错误。用户名 - 密码很好。