It's a small point, but one many people miss. When you say there is no power there, are you checking from the hot part of the socket to the ground on the socket, or are you checking from the hot part of the socket to a known ground from some place else?
It exactly 50% of all cases, it's the hot feed not there, and the other 50% there is no return feed. In many cases, they connect the grounds under a marrett, but the flimsy wire they use to connect to the actual socket gets hot and falls off the socket.