public void GetLatestTransactionDate(Action<DateTime, Exception> callback) { try { var client = new MainClient(); client.GetLatestTransactionDateAsync(); client.GetLatestTransactionDateCompleted += (sender, e) => { if (e.Error == null) callback(e.Result, null); else callback(DateTime.Now, e.Error); }; } catch (Exception ex) { callback(DateTime.Now, ex); } }