Player heads won't load on mobs

I have a command block running this command:"/summon Skeleton 2342 5 1147 {Invulnerable:1,Equipment:[{},{id:309},{id:308},{id:307},{id:397,Damage:3,tag:{SkullOwner:flashfire4}}],CustomName:flashfire4,CustomNameVisible:1,Attributes:[{Name:generic.attackDamage,Base:0},{Name:generic.followRange,Base:50}]}" previously, the head would load fine, but now it only loads a Steve head.