Most of the time, its not the people, its the process. You may want to look into why folks aren't following procedure. Maybe there is something in the procedure that can be improved so that it is easier to follow. Maybe it is not clear who is that "someone" that is to identify material on the shop-floor. Maybe the identification can be done right upon receipt of the material. Maybe there is currently no convenient place or time to record the identification. Talk to "someone" and his boss. And to the guys that need the material identified correctly. The question is not "who's responsible" but "why".
Maybe your boss can't formulate the above but thinks you should?
