Problem with empty shopping cart.

I am running the newest version of woocommerce and I just moved the shop to a subdomain.
The problem is that when I log in and log out the cart is always empty. If clear the browser cache it works again.
So if I am logged out and have a clear browser cache I can add products to the cart and everything works fine. If I log in the products are still in the cart and everything works fine. If I log out again the cart is empty and when I add products to the cart it remains empty. Now it only works if I log in or clear the browser cache. Do anybody know what the problem might be? It worked fine before I moved it to a subdomain.

https://wordpress.org/plugins/woocommerce/