You've provided food, water and shelter, but still you have no visitors.
Birds stay away when there's a predator nearby.
If there is a new cat or dog, ask the owner to tie a bell around its neck to warn the birds. Also, make sure your feeder provides adequate perching places and nearby trees and shrubs so birds can take cover. Wash your feeders with a ten percent bleach solution and let them dry thoroughly before refilling. Restock with fresh feeds. Insects and grubs provide good eating for many birds, including robins, wrens and phoebes.