MarketPress Variations Cannot add to car

Some of the products in our store have variations. These particular products end up with the "choose option" button, however they have no options to add to cart thereafter. Why is this? Please explore.

Reference link:
http://vilecompany.com/store/products/category/t-shirts/

http://vilecompany.com/store/products/mammoth-flag-t/

Thank you for your time in advanced.
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Username: wpmudev
palabra: DragonBallz