Molly, Black Lace can be stubburn to flower, and it should flower if you have another bush or not. It may not fruit without a 2nd bush. I would try Black Beauty, Laciniata or Emerald Lace. You need another cultivar for fruit, not the same one. When I think about it Nigra species is somewhat self fruitful, so you don't need a 2nd bush although a 2nd bush would make them produce more fruit. It's canadensis that is not self fruitful. If you want fruit though best to grow one meant for fruit. Bob mentioned he has Samdal a nigra species that fruits very well. Samyl fruits even better! Both can be obtained from Nourse Farms. I would get that for fruit. Lace and the others are not really great producers as you are finding out. Well some of the ornamentals produce OK Emerald Lace produces fairly well. I like the variegated species, but they too are not grown for fruit as much and require some shade. The really white one Sambucus nigra 'Pulverulenta' is tough to grow. I lost one this year due to the extreme winter. I replaced it this spring. I just like it so much, I'm still trying to figure out how to grow it well. Now the other variegated species Sambucus nigra 'Albovariegata' grows like a weed, but is susceptable to fungal disease, it needs to be sprayed. It is also a very handsome plant. Mine is getting big! I grow them at my cottage as I have low light there and am trying to find low light plants that are edible. it has been a difficult challenge. Cornus Mas though grows well there, and so I have a couple cultivars of that up there. Molly I would try feeding your bush with Holly-Tone. The PH might be too high, and the complete nutrition of Holly-Tone may help if maybe it is a lack of a micro-nutrient. Holly-Tone has sulfur and will lower PH slightly over time. Adding iron might help too. Elders like a PH of around 6.0 A soil test could help determine the problem. Sometimes in low light they will not fruit. .

yes i have seen this often with elderberry. even with well establishes patches with multiple plants, some of the berries will be great and some just dont quite make it. they take quite a while to get fully established before they produce a lot of flowers and berries. often they grow in huge patches with huge plants, you may want to add a couple of others of a similar variety to get better berries. and be patient, at least in my experience these take a couple of years to really get into their groove.

LOTS of misinformation going on here!! Elderberries - Sambucus species - are self fertile. You do NOT need two different varieties to get fruit but you will have much larger and more reliable cropping if you do. This is the same for any sort of self fertile fruit. These are caning shrubs - not trees - and do best in full sun and with reasonably moist soil. Raw fruits is perfectly edible but so astringent as to be virtually unpalatable. That's why most sources recommend cooking or otherwise 'preparing' the fruit, rather than eating fresh. Red elderberries (S. racemosa) are seldom used for berry production as they tend to be less palatable than the darker berried forms and reportedly are toxic if eaten out of hand (although they taste so bad fresh, I can't imagine anyone doing so!!). btw, as long as bloom times coincide, black elder can cross pollinate blue or American elder. Elder flowers are wind pollinated. And blue (S. caerulea) and American (S. canadensis) tend to be the tastiest and heaviest croppers of the various species.

Cut & paste from an older post of mine... Common elderberry, AKA American black elederberry, (Sambucus nigra subsp. canadensis), is native to the Eastern U.S. and grows as a bush to 6-8 feet. The European elderberry, Sambucus nigra, is more upright/tree-like, but about the same height. These both have dark purple berries. There is also Sambucus nigra subsp. cerulea, which has blue berries and is native to the West -- I've never seen one. There is also a completely different species, Sambucus racemosa, that has poisonous red berries (not purple or blue) that are NOT edible due to higher levels of cyanide (not sure if OK after cooking). For common elderberries, fruit quality depends on cultivar, although even the "ornamental" cultivars produce usable fruit. It's recommended to cook them due to cyanide content -- the toxicity is low, but eating the raw fruit can cause nausea (how much it takes varies person to person). Cooked berries are safe and make great jelly, syrup, and wine. The flower clusters can be fried.