"Failure" =1994-2002 -- Era of Clinton 'Agreed Framework': No plutonium production. All existing plutonium under international inspection. No bomb.
"Success" = 2002-2006 -- Bush Policy Era: Active plutonium production. No international inspections of plutonium stocks. Nuclear warhead detonated.
Face it. They ditched an imperfect but working policy. They replaced it with nothing. Now North Korea is a nuclear state.
Facts hurt. So do nukes.