Why my variable mode is disabled?

I have a two token collections in my foundational design system file. One is a base collection of basic hex codes and numbers and the other one is global and alias tokens which refers the base collection obviously. This file is published and is being used in another design system file which uses the tokens to create components.
I added a dark mode column in the token collection in the foundational file and the dark mode is shown disabled. Why is that and what can I do to enable it?