I couldn't find this in the FAQs, and since Sims 3 custom hairs haven't been around for long I'm guessing it hasn't been covered yet.

I downloaded the sims 3 custom hair from peggy sims AND from Sims Artist Union, and neither of them show up (there is only 1 custom hair from each site...) in the game. Is there something obvious I'm missing here? I used the sims 3 package installer and then I made sure the packages were in the right folder. I've installed several custom homes and game mods/skin tones, etc... And they all worked.

Thanks in advance for help.

If you can get other cc to show but not these hairs, then you'll need to seek help on installing the hairs from their respective creators.