I dont know if it's just my rabbit but he only'goes' when there is protection over his litter box. I tried for weeksto get him trained by leaving the litter box in an accessibleplace...but to no avail.
Eventually, after a trip to the vets, I put his carry box down and lethim run out. For that session he started using his carry box as atoilet. I left it in the same place for a few months. Eventually, Imoved the carry box under the computer desk (out the way, to give himprivacy)he still used it...later, I removed the lid so now it's justthe bottom of the carry box and to this day, he still uses it.
He'll only use it when it's clean though (I use newspaper), if for somereason it's left a little dirty, the good boy will go back and do it inhis cage litter box.
Hope that incoherent babble helps in some way.
Another thing, I think he's trained to do it on newspaper, because acouple of times when I'v left my newspaper on the floor, he's had anaccident on it, despite being perfect everywhere else.
At first, I found putting a little bit of hay in there helped attracthim in as well, I guess it's the in one end out the other philosophy.
...and he sleeps in his litter box in the cage, but when he's free, he prefers the couch.