Hi,
I tried the website and I successfully add a product in the cart. When opening the checkout page, I see the right content of my cart.
Most of time, when you add a product in the cart and the cart is "still empty", it comes from a cache problem.
Please check that you do not have the Joomla cache activate (in the Joomla configuration or by the "system cache" plugin).
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.