How do I know how many niagara particles are erased in a volume?

I made a custom niagara module to erase particles in a specific volume (distance to line and in sphere). I want player get score by erasing particles by this module.

I set “other.ErasedBullets” +1 when particle are in a volume. But it increase only 1 when module is active. It does not increase equal to erased particles.

How do I know how many particles are erased by the module ?