Cart not showing (only) on product page

Hi! I checked your site but I am unable to add anything to the cart at all. On the single product pages I don’t see an add to cart button, and on the quick view it doesn’t work (it looks like it’s successful but then if I go to the cart https://www.diligans.biz/cart/ it says it’s empty). I think this problem stems from something else…

Let me know if you have more information!
Ewout