Once a game has been canceled, it becomes permanently locked in place. You can no longer make changes to that game, including performing an undo action. A canceled game cannot be un-canceled. This is simply to avoid confusion with the officials. Officials are notified immediately when a game is canceled, and we do not want to begin confusing officials with uncancelled notices. The only way to handle that would be to manually add a new game to the system or use our dedicated rescheduling methods.