Try disconnecting the black wire from the atomizer to the regulator. Run the black from the atomizer to the negative battery connection. Also run black wire from the center pin of the regulator to the negative battery connection. I don't know if that's an alternate, workable wiring scheme, but it's not how I have mine hooked up.
Red wire:
Between positive battery connection and switch
Between switch and Vin on the regulator
Between Vout on the regulator and center pin of atomizer
Black wire:
Between ground on the regulator and negative battery connection
Between outer ring of the atomizer and negative battery connection
Red wire:
Between positive battery connection and switch
Between switch and Vin on the regulator
Between Vout on the regulator and center pin of atomizer
Black wire:
Between ground on the regulator and negative battery connection
Between outer ring of the atomizer and negative battery connection