[SOLVED] :GetPropertyChangedSignal() not detecting when a value changes?

I'm using a (server)script in a gui to change the value of a NumberValue located in workspace. The gui's script runs fine but this script just doesn't seem to pick it up. The print() statement in line 2 doesn't even print anything!

Here's the code that doesn't seem to be working:

Values.Damage:GetPropertyChangedSignal("Value"):Connect(function(changed)
    print("My damage has been changed!")
    if Values.Damage.Value == 40 then
        print("My damage has been upgraded!")
        script.Parent.Mace2.Transparency = 0
        script.Parent.Mace.Transparency = 1
    elseif Values.Damage.Value == 55 then
        print("My damage has been maxed!")
        script.Parent.Mace3.Transparency = 0
        script.Parent.Mace2.Transparency = 1
        script.Parent.Mace3.OrinthianTrail.Enabled = true
    end
end)

I need a solution that's not too hard on a computer, as my game is already kinda rough on my PC.