Add potion effect to npc

[elraro]

Hi lenis! thanks for your library to create npcs!!!

I have a problem :S im using ur NPCFactory version for spigot 1.7.9 and works great, but i have a problem. I need add invisibility potion effect to a npc, but it doesnt work...

PotionEffect potion = new PotionEffect(PotionEffectType.INVISIBILITY, Integer.MAX_VALUE, 1);

npc.getBukkitEntity().addPotionEffect(potion);

what can i do? :s: Thanks