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I also agree with keeping her in a confined room with the litter box at first - hopefully the same room that the box will remain.

I had a cat that had to have special food as well, and this took care of the issue 99% of the time. (I think we used Purina One urinary tract health) It's worth a shot.

Definitely. Everytime I've adopted a cat or moved to a new place with a cat, I've always locked them in the bathroom with the litterbox for the first few hours with some food and water. I've had kitties all my life and the only time they've ever refused the litterbox was due to illness or the wrong litter... I did have a rescued kitty once who refused to use it on account she hated my dog. In that instance, she pood everywhere the dog spent the most time; the dog bed, the dog toy box... I unfortunately had to return her because in that case she was doing it because she was clearly unhappy with her living arrangements. Most likely, your cat either doesn't know where to go or may be ill. Good luck!

I'm thirding the Cat Attract. When we rescued our first cat from a parking garage he had no clue what a litter box was. I added cat attract and put him in an enclosed area with food, water, and the litter box. Within an hour I checked on him and he had used the litter box.

I would also say to keep the litter box spotless and filled with adequate litter. The cat in mention above likes to pee over the sink drain in the bathroom every now and then. My mom was angry with this until I pointed out that she hadn't cleaned the box in probably a few weeks, and that she barely had enough litter to cover the bottom. When she keeps it clean and keeps the right amount of litter in there she has no problems. Same goes for the ferrets I had to leave with her. Animals are a lot like us, they don't want to use a gross toilet over a freshly cleaned one.

I have a male cat but the one time he did refuse to use his tray it turned out he had cystitis. It was soon sorted and we also used a cat diffuser (Plugs in like an air freshener but you can't smell it-just the cat) for a while as well, apparently it helps them not want to scent if that's the issue. We were decorating at the time so thought he might be a bit upset by it.

I second keeping it very clean too, my cat is a right stickler for hygiene xD

Also make sure the litter box is a good size for the cat, I know we bought my cat a new supersized tray as he's quite a big chap. His old one barely fit his bottom over it but now he can happily climb into it.

My female cat was a stray and must have never had access to a litter-box, because she refused to use it for a good 4+ months when I first got her. I made sure to clean the areas she soiled (outside the litter-box) with white vinegar and placed her feces in the litter-box. You want it to have their scent on it, so she'll know what it's for. You can start cleaning it more once she's used it the first few times (don't keep it disgusting, but make sure it smells like "her").

Also, try to make sure the litter-box is in a low-traffic area, and if you have more than one cat or other pets, make sure there are different ways she could exit the litter-box if she felt threatened. I suggest when she's done eating, you take her into the area with the litter-box and place her in there. Hope this helps.