I am confused about "attempt to call a nil value," what does it mean?

I barely know what this means, I know its a problem with tool.Activated:Connect(toolActivated) but I'm not sure how to fix it. I know I need to change "toolActivated" to something but I'm not sure what. Does anyone have an idea of what I change it to? The main issue is that this script sometimes works but half the time it says nil value and it doesn't work.

local sound = script.Parent.Handle:WaitForChild("Sound")
local beam = script.Parent.Handle.Attachment:WaitForChild("Beam")
local tool = script.Parent
local player = tool.Parent.Parent
local chargesound = script.Parent.Handle:WaitForChild("ChargeSound")

local debounce = false

repeat wait(1) until player.Character

local character = player.Character
local humanoid = character:WaitForChild("Humanoid")

-- first animation

local animation = Instance.new("Animation")
animation.Name = "Idle"
animation.Parent = script.Parent

animation.AnimationId = "http://www.roblox.com/asset/?id=" .. "5128762272"
local animtrack = humanoid:LoadAnimation(animation)

-- second animation

local animation2 = Instance.new("Animation")
animation2.Name = "Charge"
animation2.Parent = script.Parent

animation2.AnimationId = "http://www.roblox.com/asset/?id=" .. "5653045213"
local animtrack2 = humanoid:LoadAnimation(animation2)

-- action

script.Parent.Equipped:connect(function()
	animtrack2:Play()
	sound:Stop()
	beam.Enabled = false
	chargesound:Play()
	if not debounce then
		function toolActivated()
			chargesound:Stop()
			animtrack2:Stop()
			animtrack:Play()
			wait(0.2)
			sound:Play()
			beam.Enabled = true
			wait(2)
			local debounce = true
		end
	end
end)

script.Parent.Unequipped:connect(function()
	animtrack:Stop()
	sound:Stop()
	animtrack2:Stop()
	chargesound:Stop()
	wait(.1)
	sound:Stop()
	local debounce = false
end)

tool.Activated:Connect(toolActivated)