If you still have trouble finding the gate-lock, you can try to super-patch your game to see if it fixes any bugs. It will ask you if you want to patch your game when it's already up to date, but go ahead and do so. Follow the instructions as given:
forums.thesims.com/en_US/discussion/175477/official-ea-download-link-for-the-sims-3-cumulative-manual-update#latesthttp://That's for the PC, so if you have a Mac, go to the Mac discussion thread to get the super patch.