items not staying in cart

hello. just started working with this plugin, been playing with it for the past couple of hours. was working great until i noticed that the items are not staying within the cart when you click the “continue shopping” button. after adding new items to the cart, the old items disappear.

could you take a look? here is my page
http://www.deluxewheels.com/site/the-wheels/

https://wordpress.org/plugins/simple-e-commerce-shopping-cart/