Set?
Anyway, I have a rowan tree. It does have some berries on it, but far fewer than normal...
But what is significant about the tree is that there are far fewer leaves than normal. This is particularly noticable if you stand under the tree, and look upwards...
My guess is that the tree is in a bad way because of the very wet conditions we've been having for month's on end. But that is only a guess, and yours may be suffering from a quite different problem.