Trying to set CFrame of a model to the players left hand?

I'm trying to set the CFrame of a book to the characters Left Hand, but to test things out I tried to set it to the arm before trying to get it to the hand, and it's not working..

wait()
local Tool = script.Parent.Parent
local play = game.Players.LocalPlayer
local holdlaunch = play.Character.Humanoid:LoadAnimation(script.HoldAnimation)

Tool.Activated:connect(function()
	local event = game.ReplicatedStorage.Events.BookOn
	local book2 = game.ReplicatedStorage.OpenBook
	holdlaunch:Play()
	Tool.Handle:Destroy()
	local second = book2:Clone()
	second.Parent = play.Character["Left Arm"]
	wait()
	second.PrimaryPart = second.Parent
	second:SetPrimaryPartCFrame(play.Character["Left Arm"].position)
	local welder = Instance.new("Weld",second)
	welder.Part0 = second
	welder.Part1 = play.Character["Left Arm"]
	event:FireServer(play)
end)