Why won't my Sims 2 University expansion work?

I've had the Sims 2 for a while and just downloaded the University expansion pack. I kept using the original and noticed there was new stuff that I could pick from for furnishings and a few new actions. However, there's supposed to be colleges built into the towns and they aren't there. Since, I've learned I'm supposed to use the expansion disk to play, but it won't work. I try and it looks like it's going to work but the screen just shows a big white square that says "Sims 2 University Expansion Pack" and then it goes away and nothing else happens. I've tried looking online but I'm not really good at computery stuff so does anyone have any ideas that I should try?