BALK???

[Chris23]

I was doing a 15-16 year old game and i was working the plate and there was 1 out with a runner on 1st and 3rd. Everyone knows the move when the pitcher fakes a pick off throw to third then comes to first, I know you dont have to commit to throw to first in this situation, but the pitcher attemped a pick off towards third but didnt throw just faked then came to first where the runner broke for second but didnt throw instead he threw to second. I was taught that if the runner breaks in this situation of the fake to third then to first you have to throw to first. I called a balk the coach who it was against went wild. Did i make the right call??? Thanks in advance