Doesnt work combination Blasphemy + Despair + Decaying Hex

I try to make aura curse build, with
"Blasphemy"(Socketed Curse Skills apply in an Aura around youReserves 60 Spirit per socketed Curse)
spell and Despair curse in it and when i put support gem
"Decaying Hex"(Supported Skills inflict Decay, dealing 100% of Intelligence as Chaos damage per second for 8 seconds)
in it, it doesnt deal damage in enemies in pressence, why is that so?