Enchantment that takes more life

I'm creating an enchantment that will take three times more health from an enemy sector than if the weapon didn't have the enchantment. I already have the whole procedure ready, but when I try it, it removes the same amount of life as if it did not have the enchantment. What I'm looking for is that it be like the enchantment of Bane of Arthrophods or Impaling (I don't know how they are written in English), that is, that it does more damage to certain specific mobs. I already have the procedure but I don't know what is wrong because it does the same damage to those entities even if it has the enchantment. Can someone help me with that? I will leave an image of the procedure and if, for those who ask it, the mobs to which it will do the most damage have their own tag.