Ok the problem is solved, now there is no error anymore.
But I have a second problem, when I am in admin mode everything works great, but when I am in guest mode, it always says that the cart is empty.
Please note that I already activated payment for guests and download for guests.
Is there a special shorcode for guest checkout cart page? I used this [wpdmpp_cart] for members and guest orders age, there is nothing else mentioned in the documentation.
Thanks,
