Can't kill a Golem (Castlevania: Lords of Shadow 2)

After taking the sword of the void fighting with Golems and can't kill him. In the end, when he has no life, I'm on the F button beat him with a sword in the heart, and then have to press another button to F or RMB or Spacebar. I do, but nothing happens, it is restored to the mid-line of scoria all over again. So I have 2 days, what's the matter can't understand. And yet, there are no converging circles, just popping up to press many times one of these three buttons and all. What to do?