She seems to give me signals that she likes me, but when I approach her she always blows me off?

I have seen her looking at me many times, we have only talked once and that time she gave me pretty good signals, she has smiled at me in a flirty way, but always when I approach her, she is always blowing me off (aka ignoring me or walks away from me) what is going on?.
She seems to give me signals that she likes me, but when I approach her she always blows me off?
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