I'm trying to make a trail shop and I'm currently stuck on the phase where my Module Script returns this error:

ReplicatedStorage.ModuleScripts.Insert - attempt to index nil with 'Parent'

I've searched around both scriptinghelpers and the Roblox Devforum but I couldn't find the answer to my problem. Here's the code:

module.InsertTrail = function(plrname, trail)
	local plr = game.Players:FindFirstChild(plrname)
	plr.CharacterAdded:Connect(function(char)
		local at0 = char.Head:WaitForChild('Attachment0')
		local at1 = char.HumanoidRootPart:WaitForChild('Attachment1')
		
		
		local tr = trail:Clone() 
		tr.Parent = char -- Error Line
		tr.Attachment = at0
		tr.Attachment1 = at1
	end)
	
	game.ReplicatedStorage.Trail.OnServerEvent:Connect(function()
		plr.Character:FindFirstChildWhichIsA('Trail'):Destroy()
	end)
end

Any help will be appreciated! :)

Anonymous