Error while trying to use LocalTransparencyModifier, what's the reason?

Hello, Devs!

I was making FPS game in Roblox from YouTube tutorial and everything worked correctly until this moment. I written script perfectly as he and in the same location. Errors are on the bottom of the question.

CODE:

local player = game.Players.LocalPlayer

local model = game.Workspace:WaitForChild(player.Name)

local rightLower = model:FindFirstChild("RightLowerArm")
local rightUpper = model:FindFirstChild("RightUpperArm")
local rightHand = model:FindFirstChild("RightHand")

game:GetService("RunService").RenderStepped:Connect(function()
	
	rightLower.LocalTransparencyModifier = 0
	rightUpper.LocalTransparencyModifier = 0
	rightHand.LocalTransparencyModifier = 0
	
end)

ERRORS:

Workspace.ErktikyYT.Arms:9: attempt to index nil with 'LocalTransparencyModifier' line 11,12,13

try moving everything besides the player variable into the renderstepped function.