Not give EXP if the NPC has a Value?

So I want it to not give EXP when the NPC has the Value, but it still gives EXP even though there is a value inside the NPC. Why is that? I am guessing on line 11 "if not", is suppose to be written differently?

local debounce = false
local objectValue = Instance.new("ObjectValue")
local player = game.Players.LocalPlayer

function onTouched(hit)
    if not debounce then
        debounce = true
        if hit.Parent.Name:sub(1,17) == "AFK Noob Lv 1 HP " then
            hit.Parent.Humanoid.Health = hit.Parent.Humanoid.Health - 25
            if hit.Parent.Humanoid.Health == 0 then
                if not player.Character:FindFirstChild('Value') then 
                    player.leaderstats.EXP.Value = player.leaderstats.EXP.Value + 16 
                end
                objectValue.Parent = hit.Parent
            end
            wait(0.5)
            debounce = false
        elseif hit.Parent.Name:sub(1,4) == "Noob" then
            hit.Parent.Humanoid.Health = hit.Parent.Humanoid.Health - 25
            wait(0.5)
            debounce = false
        end
    end
end

script.Parent.Touched:connect(onTouched)