If you only have one elderberry it is likely the problem. Elderberries need a male and a female to produce. If there's not one in the area to pollinate and you don't have one planted you won't get much in the way of berries if anything at all. If there IS one nearby you should get SOME berries albeit a smaller amount than if you had one close by. I think my second season had scant berries...but the third it fruited prolifically. I ended up having to take mine out...they were taking over. My solution was to cut them back hard to try to contain them which, of course, caused it to sucker unmercifully. So as much as I loved having elderberries, my property was too small for them to be manageable and frankly, the only things bothering with them were a couple mockingbirds and robins. I had hoped for a wider variety...but I guess the natural habitat around me is so plentiful that it did not draw any other fruit eaters.
Robin

If you only have one elderberry it is likely the problem

You don't need two elderberries to get a BLOOM. And there are not male and female plants. If that were so, then sambucus would be dioecious (definition below). It is not, it is monoecious.

Definition: A plant species is said to be dioecious when its male and female reproductive organs are carried on separate individual plants of the same species. When a plant species is dioecious, at least one male plant must be present in a group for the fruit-bearing female plants to be pollinated. By contrast, "monoecious" plants are plants having unisexual reproductive organs or flowers, with the organs or flowers of both sexes borne on a single plant.

You don't even need two plants to get berries, but you generally get more berries due to cross pollination.

Back to the original question. I think next year will be the year for you, assuming that these plants ARE getting enough sun. They all would do better if they get about 5-6 hours of sun. They do need sufficient sun to flower.

Good luck!

I wouldn't worry about your shrubs, it does take them a few years to begin blooming. The sun should not be a factor for either the dogwoods or the viburnum because they are under story trees. Just give them a little more time, they will probably bloom in a year or two. My viburnum did not bloom until it was about 5 feet tall, (and it is in shade).

Thanks for the info and encouragement. I'll try to be patient.