Why its error:attempt an index nil with 'Transperency'?

btw im new hehe help me please

function onTouch(part) 
local human = part.Parent:findFirstChild("Humanoid") 
if human ~= nil then 
part.Parent:findFirstChild("Torso").Transparency = 0
part.Parent:findFirstChild("Left Arm").Transparency = 0
part.Parent:findFirstChild("Right Arm").Transparency = 0
part.Parent:findFirstChild("Left Leg").Transparency = 0
part.Parent:findFirstChild("Right Leg").Transparency = 0
part.Parent:findFirstChild("Head").Transparency = 0
end 
end 
script.Parent.Touched:connect(onTouch) 

local CharacterName = "Xapelize" -- Set this to the player name you want to hide

game:GetService("Players").PlayerAdded:Connect(function(player)
	player.CharacterAppearanceLoaded:Connect(function(character)
		wait(0.5) -- Some debug
		if character.Name == CharacterName then -- Detect if it's the PlayerName
			for _, DetectingPart in pairs(game.Workspace:WaitForChild("Xapelize"):GetChildren()) do -- Get everything on your character
				if DetectingPart:IsA("Accessory") then -- If it's accessory
					DetectingPart.Parent = game:GetService("ServerStorage") -- Set the parent to ServerStorage (stores accessory inside it so you can get it back anytime)
					print(DetectingPart.Name .." is an accessory")
				elseif DetectingPart:IsA("MeshPart") or DetectingPart:IsA("Part") then -- The reason why is there part is because Head is a Part
					DetectingPart.Transparency = 1 -- Hide it
					print(DetectingPart.Name .." is a mesh part")
				else -- Neither Accessory nor MeshPart nor Part
					print(DetectingPart.Name .." is neither accessory nor mesh part, it's a ".. DetectingPart.ClassName) -- Print some stuff
				end
				
				if DetectingPart:IsA("Part") and DetectingPart.Name == "Head" then -- If the DetectingPart is head
					for _, DetectingChildrenHead in pairs(DetectingPart:GetChildren()) do -- Get the children of Head
						if DetectingChildrenHead:IsA("Decal") then -- If it's a decal (face)
							DetectingChildrenHead.Transparency = 1 -- Hide face
						end
					end
				end
			end
			
			print("Character".. CharacterName .." is invisible")
		else
			print(player.Name .." is not ".. CharacterName)
		end
	end)
end)