get a bigger litter box if possible! My neighbor had the same problem so he took the out the litter box and that ruined everything! She did her buisness all over the wooden cage and then my neighbor had to get a new cage. Once he got his new one(the same cage model, just new) he put a bigger litterbox and it worked wonders on the little bunny! It was to heavy to be moved so she couldn't lift it and it was bigger so she would go into the litter box to sit! once she was already in it why not do her buisness in there? lol...well anyway, glad to help!
charliesangel88