DamageCause=ENTITYATTACK, and PROJECTILE returns "UNDEFINED" when damagemodifiers are on -1

this variable "<skill.var.damage-type>" returns "UNDEFINED" when a mob has damage modifiers on -1 or any negative number (cure) with damage type mechanic (like ICE for example) just on entyty attack and projectile damage causes, other causes works fine but not the principal ones, therefore is not damaging the mob if you have a sword or a bow.