replaceitem entity command not working on villagers

The slot.villager tag does not work. When you run the command it says it was successful but when you look at the villager nothing has happened. Here is the command I used.

/replaceitem entity @e[type=Villager,r=2] slot.villager.1 minecraft:iron_hemet

After the stot.villager tag I have tried many numbers other than 1