How long have you had her for? Penny was scared at first, but started enjoying it when she went more often. Skyhigh suggested a good thing, bring treats or toys, be very enthusiastic and happy when you take her outside. If you've only had her for a short while then i'm pretty sure she'll get over it soon. If you've had her longer you're gonna have to work on it a bit harder. Make being outside a good fun experience for her and she won't be scared no more. Penny loves going outside now... except when it's dark, she doesn't like that too much lol.