Instruct: Classify Amazon reviews into positive or negative sentiment
Query: didn't work for me

We have to have the litter box in the apartment, can't put it outside, and this one didn't work for us. Luckily, I was able to return it.Cons: (1) the litter crystals scatter all over the apartment, step on one with a bare foot, and an "ouch" is guaranteed; I wonder how the cats feel about it; (2) depth of the litter layer is too shallow - common problem for all auto boxes I tried - cats end up scratching the laminated bottom of the box.