My Sim won't age?

I have a Sim who has a husband, twins, a son, and triplets (I know, but is what they wanted). The son is at the point in his life where he is supposed to change from teenager to young adult. I have tried the cheat, I have restarted the game multiple times, I have had him blow out his candles on a daily basis and after he blows out his candles he just keeps living as a teenager. I've even deleted the caches that another Yahoo Answers question had suggested. I've also tried extending the days so he could be a teenager longer and see if that would fix it. Nope. He is a werewolf also. The triplets during this weird time all aged on THEIR birthdays, so why isn't he? Any suggestions?