Born in 1999

I was on February 1, 1999. I am mistaken to be a rabbit every time, but I've looked up my birthday and birthday year in almost every Chinese zodiac book and other stuff & it has came up that I am a tiger. One of my friends mom thought I was a rabbit until she asked me because I didn't act as a rabbit, she found out that I was actually a tiger. Why is it that I'm a tiger but mistaken as a rabbit?