The lat pulldown is for your lats, rather than your shoulders.
You have an exercise for the front deltoids and the medial deltoids, but you need one for the rear deltoids. Bent over raises, such as goinforthegold mentioned, is for the rear deltoids. Sit or stand and bend over; raise your arms towards the back like a butterfly, holding dumbbells.
If you do a lot of chest work, the front deltoids get worked quite a bit. It's the medial and rear deltoids that can be neglected.
Do or don't do; there is no try (Yoda)