Checkout doesn't reflect price variation

I am adding products to my online store. The price varies with the monthly term. I designated this pricing in the Variations section, but when I go to the Store page and click on, say 6 month pricing, the original price that is required under Product Name is shown. How do I set it up to reflect the pricing in the Variations section?

http://wordpress.org/extend/plugins/wp-ultra-simple-paypal-shopping-cart/