I haven't grown eggplant very often so am not that experienced with it. I do know it takes a longer season to grow them than some other veggies. You said they were in the shade, that was likely a big factor. Another might be that the blossoms were not pollinated.
With most tomatoes, which are in the same family as eggplant, blossoms also will drop if it's not warm enough over night. I think that's in the mid 50*F. Perhaps eggplant has a similar warmth requirement. Just a guess.
Hi Dendra yes I think they may need warmer weather and we are in a cooler area... as I live about 30 miles from the Monterey Coast.. and this year was a cooler than normal summer.
I plan on starting them sooner and putting them in the full sun next year which will give them some warmer temperatures.
Or maybe I will just grow the japanese kind next year which LOVE our climate here and produce massive amounts of eggplant here.