Why does this script work when I test it solo in studio? [ANSWERED]

Why does this script work when I test it solo in studio, but when I play the game, it doesn't work? I have to drop the weapon and then pick it up to make it work. Can someone fix this please so you don't have to drop it to fix it?

local animation = Instance.new('Animation')
local animTrack
local debounce = false
local player = game.Players.LocalPlayer.Character

function onEquip()
   script.Parent.Handle.UnsheathSound:Play()
end

function onActivate()
    if not debounce then
    debounce = true
    if player:FindFirstChild('ForceField') then player.ForceField:Destroy() end
    animation.AnimationId = "http://www.roblox.com/asset/?id=129967390"
    animTrack = player.Humanoid:LoadAnimation(animation)
    animTrack:Play()
    script.Parent.Handle.SlashSound:Play()
    script.Parent.Handle.Script.Disabled = false
    wait(0.5)
    animTrack:Stop()
    script.Parent.Handle.Script.Disabled = true
    wait(0.5)
    debounce = false
    end
end

function onUnequip()
    animTrack:Stop()
end

script.Parent.Equipped:connect(onEquip)
script.Parent.Unequipped:connect(onUnequip)
script.Parent.Activated:connect(onActivate)