Why do the other Cyclopes fail to help when they respond to his cries for help ?

Odysseus cunningly told the cyclops, Polyphemus, that he was named "Nobody". As a result, when Polyphemus was screaming in horrible pain after Odysseus (Nobody) stabbed him with a stake in the eye, the neighboring cyclopeses yelled to Polyphemus to see if he needed help. Polyphemus responded that nobody was attacking him.