Upgrading a Weapon's attack damage and/or speed

Hello developers, i have a kind of stupid question, but i can’t figure this one out without help. So the problem is that i have a widget called FIGHTMENU and an actor called PROJECTILE, what has a damage on it if it overlaps with an enemy character.

so i tried making a reference in the widget plueprint to the PROJECTILE , and if i click on the button called WEAPON DAMAGE +1 then SET DAMAGE to -100 (from -50)

but when i tried it in game, it didn’t worked for some reason. What could be the problem?