In some of the later expansions, they might only respond if you target them while hailing. Or they might have made hail do a target check now; you used to be able to type "Hail, npcname" in a text box and if the npc was nearby, he would respond.
If you have an active account and want to try this, try going to the Ak`Anon bank and say the word "guild". Tell me how many responses you get
