How do you put custom content for sims 3 on mac?

i have a macbook pro & im trying to install sims3pack files into the game. when i click on it, it says "unknown error occured". does anybody know why this is happening? i have all the expansion packs and i play with the late night cd. do i have to put the sims 3 base game in to install it? please help, ive tried EVERYTHING.