Bug on Cursebringer helmet

Hello!
The Cursebringer helmet have to grow a purple power on character head when we curses a enemy.
But if you using the curse as a aura with blasphemy gem, curses on hit on itens, skitterbots or spell totem gem to do the curse, the effect of helmet will not to happen. Needs we curse enemy with only the curse gem without any other method, is it a bug? Im very desapointed with it, I love the set and this effect on helmet.
All other parts of the set works well, the imp, the frogs and insects.