You know as we become older, we become less trusting and more
suspicious of people in our later stage of lives. In most cases, at
least what i witness is that more ladies choose to fall back and
get attached with guy friends in their primary, secondary, JC,
poly/university friends because of the long years of bonding and
trust in their guy friends.
For you, being a totally new stranger, she is freaking afraid of
you because she does not know you. You could be a jerk or maybe you
are.(just that you do not realize it yourself).
Please take things slow. I advocate NO MORE asking her out
one-on-one. Organize a group date instead. Go ask a few other
colleagues before you ask her out. Go out in a group date because
in a group date, you will be yourself. There will also be less
pressure, and more avenues for the girl to observe you.
Going on One-on-One date, is really a superficial date because both
parties will be on pretence and be at their VERY BEST.