PK forward inside keeper's box

[tornado]

During my daughter's recent soccer game, the opposing team was lining up to take a PK. One of their forwards was standing just inside the keeper's box, along with the player taking the PK. After the whistle the player scored on the PK. Then the AR went to the referee & told him about the 2nd player in the box. He awarded our team a goal kick.
Was this the right call? What if this player had been outside the box, but 17 yards or less from the goal line?

Thanks for your answers!