Damage not consistent and script breaks in a Damage script?

Hi, i have a pretty weird problem with my script: Basically, I'm making a weapon, and it should only take damage when it's activated. The purpose of this is to avoid the player from just walking to a humanoid, and it takes damage, so they have to activate it. It works the first time, but then after a few times I don't have to activate the tool for it to do damage, and it does like 100 damage