Kitten won't use litter box, tried everything?

Got my 8 week old kitten home about 5 days ago but she only uses the litter box if I put her in it, the litter box is in the bathroom and away from her food, its scoop away litter. I've tried locking her up in the bathroom at night and she uses it while shes in there but when I let her out to play she goes on the tracking of my sliding glass door through out the day, I always bring her straight to her box when shes going.the litter box is a kitten size box with about 2 inches of litter. What can I do?!