Section 106 of the Easements Act: A Paradox of Rights

I'm completely lost, guys. We were studying Section 106 of the Easements Act and I'm just stuck. According to this section, if a permanent nuisance is created and the owner of the dominant heritage knows about it, then the owner of the servient heritage can claim compensation. But then I read somewhere that if the owner of the dominant heritage didn't know about it, but the nuisance is still causing harm, then the court can order for abatement without compensation. What's the deal here? Is it a case of caveat emptor or not? How can the court just suddenly change its rules like this? It's like saying, "Hey, if you didn't know, it's okay, but if you did and didn't do anything, tough luck, you pay up!" Someone, please clarify this contradiction.