More than one product for the Image Lightbox in Marketpress

I would like to know how to add more products to the Image Lightbox used in the Marketpress plugin. When you click on a product image of a single product page in the store the Image Lightbox works fine and show a number "1/1" on the top right part of the picture, what let us suppose the possibility of having more than one image there. But how to do it? What is the secret? Here you are one single product page of my dev site: Marine Corps Bulldog.
Thanks!