My Mac OS X wont play Sims 3, please help!!!

My Mac OS X wont seem to play my Sims 3 game, the weird thing is that I had installed in before and it had worked fine (I had had to uninstall it though as it was a friends game). I bought my own game but after I had installed it, an error message came up saying that it can't verify the game!

I then contacted EA help line and they couldn't think of anything (and weren't very useful -.-), I even bought another Sims 3 game but the same message came up.

To be completely sure, I installed the game onto my old PC as it is meant to play on both PC and Macs and it works fine on my old PC, so why not on my mac, please can someone help!!!