Sims 3 Product code only showing up for expansions.

Hi,

I only have one product code for two games. A couple of years ago I bought the disk for Sims 3. I also bought the expansion World Adventures. I just recently tried to play it again by downloading Origin. When I made my Origin account and downloaded the launcher, both my games were there. However I was only presented with one product code for both games. The product code works for the expansion, but not the original game. I was wondering how I might be able to get another product code or something to download the main game.

Thanks.