Have you tried the pine pellets? i know my kitten would not use the pine sawdust type stuff which my other cat loved and she would not use any clay or any other kind of litter. Now they each have their own litter box, one has the pine sawdust type stuff in it, and one has the pine pellets in it. here is a link to what I use. I love the pine stuff and am so happy my kitties like it.
http://www.petacular.com/products/Feline-Pine-20.html it is more expensive then the normal clay litter but I personally like it way better, no dust, and it smells like christmas.