The summon durnehvir shout doesnt appear to be working

Unlock all three words, aim at an open space on the ground, and outside.

Soul Cairn -> Unerworld...Under....World.....

You have to aim at the ground, and please use the search bar before creating a topic. This question's been asked before.

Aim it at a large area preferably a flat one. It has to be enough space for the dragon to land on the ground