Elderberry Crop Failure

This year many if no most of my elderberries fell off the bushes just before they were dead ripe. I think it was due to dryness. First I thought it was birds eating them even though I did put nets over them, sort of,.... (it wasn't a very good netting job). However there were lots of little - not quite ripe- elderberries all over the ground. I checked the berries for fruit fly maggots and didn't see any, although 2 farms near me had fruit flies ruining their blueberries. I did make one batch of crabapple-elderberry juice which I plan to can tonight. I still plan to make aronia-schizandra juice and grape juice.