The Gemara discusses whether a fence made with just Shesi (horizontal component) or just Eirev (vertical component) is a wall. Some opinions say that its not.
Then there is another Gemara which discusses whether a tree with branches sticking up is considered a diomed, or whether sticks with breaks under 3 tefachim can be called a diomed.
I don't understand. In all of these cases we should say Lavud.
When do we say Lavud and when when do we not?