Ad agency Wieden & Kennedy has got Nike into another fine mess. Nike now faces a $1m lawsuit after the agency allegedly used a piece of music in an ad without the author's consent.Singer, Billy Paul, is seeking $1m in lost licensing fees in a suit filed in the federal district court in Los Angeles, after claiming that the company had not sought his permission to use his song, "Me and Mrs Jones".Wieden & Kennedy, also being sued by the singer, said it seemed like it was "a very stupid mistake".The question has to be: how long can the Portland-based ad agency hold on to the lucrative Nike contract? Two of its ads for the sports giant had to be pulled in October after they caused a deluge of complaints.