What do you do after you've beaten the 7 Sages in Pokemon Black?

Please, Someone help me! I've beaten the Elite Four the first time, and I found the 7 Sages, then I was told that I would find Looker in Black city, and he gives me the Dark Orb, but I can't find Looker in Black city. ANYBODY PLEASE HELP!!!!! By the way Looker is the guy who tells you to find the 7 Sages, so yeah PLEASE HELP!!! I would really really appreciate any answer!!!! PLEASE HELP!!!!!!