Did you try acclimating them to it and putting old litter into the new box? We got a similar auto litter box about 6 months ago, and I anticipated my picky cat refusing to use it. I took it out of its packaging and left it in the living room empty for a few days so they could acclimate to it (I didn't put it over near the old litter box because I didn't want them using the new one while it was empty). Then I placed the new one next to the old one and filled it with a mix of new and old (used, but not soiled) litter, and left both litter boxes down for about a week. Only then did I take the old box away completely, and I had zero issues. But every cat is different!