Suet might be more appealing to a different set of birds than the usual urban ones - woodpeckers, woodsy species that would come around if you have enough trees and greenery. So it's probably a location issue. Seed eaters don't mind living in more urban settings: sparrows, finches, doves, pigeons, etc.
And as far as hummingbirds go, I think that the ruby-throated hummingbird is a summer resident of the entire Eastern half of the US, so it would be a seasonal thing to put up a feeder. If you have any plants on your balcony (esp with red or orange flowers) that would be a further attraction.