Complete My Season won't show up

I've bought a bunch of episodes from The Simpsons Season 3 (which I know is eligible for CMS) but for some reason it won't show me the Complete My Season price. It does however give me the option on Season 2, of which I have bought less episodes.

If I click the $24.99 price to buy do you think it'll use the CMS price I'm not seeing or charge me $24? Any ideas on how to get it to show up? I'm on an iPad running iOS 6