Promo code ALWAYS invalid?!?

I have two expansion packs for The Sims 3 and so I subscribed by email to get offers and also I get them from Origin. So I click the link, I enter the promo code and ALWAYS  A-L-W-A-Y-S  it says invalid promo code and I have missed out on getting, like 5 expansion packs all 75% off!!!!!! Why does it do this and how can it stop?!?!