Sims 2 Ultimate Sims not aging

Hi,

I have downloaded the Sims Ultimate Collection and everything on the game appears to work fine except my sims wont age. I have tried the boolprop cheat and tried to force them to age in the various ways through that and still nothing. The sim gets taken to their birthday but then regresses back to the start of their current aging process. I don't have any aging cheats on and have tried using a birthday cake etc but nothing seems to work. Can anyone help? Even if it's a technical solution.