Noob question re customised 'weapons'

[Zimrathon]

Hi,

Very new to HLO and would love Age of Ashes content to be available but as it isn't I'm having to create the content for those not appearing in the bestiary.

In Hellknight Hill there is a new creature called Hellcrown which has a ranged attacked called 'Nail' whose base damage is 1d4+2.

I've added a custom ranged attacked called Nail but for the life of me cannot get the +2 onto the 1d4 (either by using the table selection or specifically indicating 1 dice at d4).

I've used the 'Ranged Damage Bonus' field but that appears to do nothing.

Am I being dumb or simply missing something.

Ta