I have 6 cats total. The youngest one wont use a litter box.?

I have 2 cats that are almost two, 3 cats are 9 months old and the youngest is 5 months old. The youngest one has never used a litter box. she came from a litter of four, was born in our home, her mother is one of the 2 year olds. The other kittens in the litter used a litter box and have since been placed in homes.The one I have left has one spot she always goes, but when i put a litter box there she wont use it, she still goes on the ceramic floor. what do i do??? I have multiple litter boxes and they are cleaned every day. I have tried various types of litter and styles of boxes. Is it possible that she will never use the litter box?? I have never had this problema and have owned cats for years. what can i do.