I don't know if this is a dumb question, but my Sims game won't take any custom Sims from MTS. Like I understand that some are made for specific expansions but only 2 of the 20 I've tried have worked. Most of them are labeled "Basegame" but before I got OFB to BV I had Uni and NL and they all seemed to work. The message pop's up saying "This content requires Expansion Pack data that is not installed". But I have downloaded certain Sims before but now they don't work since I've upgraded to more expansions. Something doesn't seem right about it. Is there a way to fix it or is it just Expansion pack errors?

You'll want to use the Clean Installer instead of the default installer, as it goes around the problem.

It also helps for installing houses (you will usually need the proper EPs, especially AL/M&G if the house creator have those because it's a compatibility issue with the game engine - but if you lack a SP except for the case of M&G it's usually not a problem).

THANK YOU SO MUCH! This fixed everything!!! :D