we have two five-week kittens, and are attempting to litter train them. we got them a new box (the one we have for momma has a roof, because she's a nutty digger), and new litter. Sasha won't use theirs, but I thought that the mother was supposed to train them. We're using scoopable for her, and something else for the kittens. They are still quite content just to go on the towel in their room, and not use the box. Any advice?