She is probably agressive when you stick your hand in her cage becuase you are invading her territory. How big is her cage? Is she allowed time out of her cage every day? If her cage is in your room, try letting her out with the door to your room shut and all cords covered or protected. Do NOT approach her, let her approach you. You need to gradually build her trust in you. Many, many, many rabbits with try to attack a hand stuck into their cage, but are freindly when they're out and about.

You need to remember that rabbits, in the wild, are prey - everyone is out to eat them, so picking her up can be seen by her as prelude to death.