If you are attempting to add a product to your shopping cart on your website, and you click on the buy button, and the next page you see tells you that the cart is empty, then you should try the following as the first attempt to resolve the issue:
Check that your web browser has cookies enabled (do you have problems staying logged in to other sites? This might suggest you have them turned off). You need to have cookies enabled on your browser for your website to work.
Try quitting your web browser (closing all windows, and exiting the browser completely), and then re-opening it, in case your browser is having a temporary issue.
If after doing both of those things every time you add an item to your cart you are shown a cart is empty page, please email us with details of which browser, browser version, operating system, and operating system version you are using.