Where does your kitty sleep? Some cats don't like their litter tray to be too close to where they sleep or eat.

A lot of cats don't like the crystal if they had something different before. It feels different underfoot and it also makes a funny sound when they pee on it which scares some cats and they won't go back again.

With cat urine stains in the carpet its true about bleach, don't use it because cats will always go back and use that same spot again. You can use an enzymatic cleaning agent like Biozet which is available in the laundry section of the supermarket. It breaks down the stain and neutralises the odour as well. I used to work in the animal health industry and this is what we recommended our customers use when cleaning cat urine stains.

HTH