Keygens don't work, just use any key to install the game, get the 1.4 and 1.5 patch, then use a cracked server on which to play. If you wanna play without a valid key and without a crack, disable punbuster and use one of these servers, all are free:
69.156.12.38:28960
212.45.52.231:28961
83.133.124.64:28964
(open the console and type connect (server IP & port))