Is this your first "relationship?" I only ask because I can probably give a better answer if I know where you're coming from.
How did the date go? Did you seem to have a lot in common? Good conversation? Did you both seem to have a fun time?
It seems like one of a few things could be happening:
1. The date did not go well, she realized that she didn't really like you and is pretty much done with everything. If this is the case, then I would move on.
2. She had a good time, but she doesn't want people at work to be in her personal business. Ball's in your court.
3. She's doing that weird girl thing and playing hard to get. She's waiting for you to make a move.
4. She wasn't ignoring you, you just weren't saying anything and possibly projecting false motives on her due to personal insecurities. Time to change your perception of yourself.
5. Could be many other reasons. People are unique. Cookie cutter answers tend not to be the best for relationships. Everyone and every relationship is different.
Been in relationships with people at work. None of them worked out in the end, but I don't regret any of them. Personally, I don't want everybody up in my personal business. I didn't show a whole lot of affection at work, but I did talk to the other person. One of the girls and I flirted at work pretty blatantly, but no one knew we were actually together except close friends at work. The only guy I dated at work said he was bi like me, but he was still in the closet (and very confused about his sexuality), so there was obviously nothing more than friendly conversation there and maybe the occasional taking a lunch break at the same time. There was another girl that I dated for a year or so. We'd eat lunch together, quick kisses, hugs etc. No making out at work. We were pretty serious, so I'm pretty sure most people knew about our relationship. There's another girl that I hang out with from time to time. We talk everyday at work and no one thinks anything of it afaik.
I guess the point I'm trying to make is that there's no real definition of what a work relationship should look like. Maybe invite her to dinner and get to know each other better. If you have her number, try texting her. If she responds that's a good sign. I just wouldn't count the relationship/friendship over if you like her. Just go after her bro. What do you really have to lose? Just don't let this one thing make you think it's over. I'd rather know she's not interested and move on rather than assume she's not interested and wonder "what if..."