Problem with doomblast

Can smb tell me why doomblast doesn't work on my pathfinder? It works only on 2nd cast. When i switch gear with occultist everything works.

My one is working on one cast but I don't know why I am doing zero damage. Maybe you can figure out your issue with my pob. What I read with the two cast issue is that either cast speed or cooldown reduction is missing in the build.

If anyone could take a look at my build and tell me what the f I did wrong to end up with such low damage, I would really be happy. Thanks guys!

POB: https://poe.ninja/pob/mf8