If the age restriction is 6+, then I can't imagine on what basis could they not let your son in, since there is absolutely no way to find out his exact age at the doors to the arena. But for instance Stockholm has a 13+ years restriction! I gues they might make problems. It is hard to believe that a 12 year old kid can not go to a RS concert, since those kids were the majority of their audience at the very beginning. Maybe the promoters are affraid of the same riots that happend in the sixties?