public void LoadAllTransactionImages(int transactionId, Action<Exception> callback)
            {
                //ICollection<TransactionImage> existing = null;

                App.Instance.StaticDataOnlineStatus = App.Instance.StaticServiceData.SetServerStatus(status =>
                {
                    if (status != Model.StaticServiceData.ServerStatus.Ok)
                    {
                        //## doesn't need to get anything from cache. Images are retrieved by the transaction
                        callback(null);
                    }
                    else
                    {
                        try
                        {
                            var client = new MainClient();
                            latestState = Guid.NewGuid().ToString();

                            client.GetImagesForTransactionCompleted += (sender, completedEventArgs) =>
                            {
                                if (completedEventArgs.Error == null)
                                    SetupTransactionImageList(completedEventArgs.Result, transactionId);

                                callback(completedEventArgs.Error);
                            };
                            client.GetImagesForTransactionAsync(transactionId, latestState);
                        }
                        catch (Exception ex)
                        {
                            //var msg = string.Format("There was an error accessing the weather service.\n\r{0}", ex.Message);
                            callback(ex);
                        }
                    }
                });
            }