Please HELP!! We have four cats. Three of them use the litter boxes for every necessity. The fourth only uses it to urinate; to mess she goes in a corner of the dining room.It is driving us crazy and we have tried many things: a professional cleaner made for animal waste, strong perfume, black pepper, scented candles, and even sticky tape. Nothing works!!
Any ideas before I am carted off to the insane asylum?

Kristen,
Couple of questions, has this cat always done this or is this something new? Have you changed the type of litter you are using? Does the cat have to share the litter boxes with the others? Is the litter box in a high traffic area?
Some cats really like their privacy so you might consider giving this cat its own litter box and placing it in a very quiet and private area. If this is something that has happened since you got her, you should contact your vet and ask for suggestions.....Mary