KVO dependent keys

According to the documentations there are now two ways to declare dependent keys for KVO (apart from deprecated ways): override +keysForValuesAffectingValueForKey:, or implement a method +keysForValuesAffecting<Key>. Is this true?

My problem here is that when I do the former, the KVO dependency does not work, but when I do the latter it does work. So is this an implementation bug or a documentation bug, or am I misreading the documentation?

BTW I want to override the general method because I have a lot of keys that have the same dependencies, so it seems more natural to override one method rather than implementing a large number of specific methods.

Christiaan