Characteristics not displaying

-- HikaShop version -- : 3.1.1
-- Joomla version -- : 3.7.2
-- PHP version -- : 7.0.1
-- Browser(s) name and version -- : Chrome 59.0.3071.115
-- Error-message(debug-mod must be tuned on) -- : No error message

I have added a characteristic to a product on a test site. It correctly shows "Choose options" instead of "Add to cart" in the product listing, but doesn't display the options after clicking the button.

My bad. I hadn't added the variants.