Putting a bit of hay or a favorite toy at one end of the litter box will encourage its use. This serves only to frighten the bunny and it is NOT the way they learn. Watch your bunny and learn her habits, likes and dislikes. Knowing your bunny and being willing to compromise with her are the best ways for her to learn-and become a happy house rabbit. Instead use a safe, natural litter such as Clean N' Comfy or Yesterday's News.
Litters made of recycled plant fibers and recycled news print are also good.