why is the button to declare war inactive?

I have noticed that In Kingdom view, Diplomacy tab Propose peace and Declare war buttons are always disabled

I think you already know about this, but I didn’t find a similar topic, and I saw a problem on the Internet for a certain number of people, and so, the button for declaring war and signing the peace is not active, and wars themselves happen all the time, I think that they are declared by the...