@asuservice, there are a few different shortcodes to display the shopping cart (each has it’s uses). The one you are using only displays the shopping cart when there are items in the cart. Please use the following to always display the shopping cart:
[wp_eStore_cart]
Remember all the available shortcodes for this plugin is listed in a PDF file at the following URL:
http://www.tipsandtricks-hq.com/ecommerce/wp-estore-shortcodes-and-functions-reference-460