activate essential addons elementor error

I am using caldera forms together with the elementor page builder (both in free version). For better integration I have installed “Elementor Caldera Forms”. From the getgo all elements are disabled. When I try to enable any of them I get prompted with the error message: “Install Essential Addons for Elementor”. The Essential Addons for Elementor is installed, however, the caldera-element within the essential addon is activated.
I tried de- and re-activating both plugins (“elementor caldera forms” and “Essential Addons for Elementor”) without success.