Mistake? How is that a mistake? You will find out what you want to know... good or bad. Most women make their minds up right away about which guys are friends, and which guys are potential lovers. If you never do anything, believe me you'll be a "friend."
Not entirely true.
I am in a relationship, and we fooled around alot, but the girl didn't want me as a boyfriend initially because she had just gotten out of a long, arduous, and painful relationship with an overly obsessive guy. We became friends, and she still instigated things from time to time... I was dating other girls at the time also. Eventually she felt comfortable knowing me for awhile to realize I wasn't going to be like her ex-boyfriend, and knew I would treat her well, and we got together.
Sometimes they are just "testing the water" so to speak, as keeping you a friend for awhile... you learn the truth about someone as their friend... moreso than you can learn on a couple of dates... keep that in mind. We are now together
However I do agree, if you don't make a move from time to time, then they will think you aren't interested. Out of sight, out of mind. Show some interest in her, and mention that other girls are interested in you also, and she'll get jealous and you'll be snatched up in no time...