private void OnUserInviteButtonClicked(object sender, System.Windows.RoutedEventArgs e)
        {
            var username = UserTextBox.Text;

            string factoryString = (string)FactoryDropdown.SelectedItem;
            int    factoryID     = HelperFunctions.GetIdFromFactoryString(factoryString);


            String  message = "User " + username + " konnte nicht hinzugefügt werden.";
            Boolean success = csu.AddMemberToMemberAccess(factoryID, username);

            if (success)
            {
                message = "User " + username + " wurde erfolgreich zu " + factoryString + " hinzugefügt";
            }
            ShowPopUp(message);
            UserTextBox.Clear();
        }