Why does this union not turn neon when I click a GUI Button?

local Button = script.Parent
local OtherParts = script.Parent.Parent.Parent.Parent.Parent
local Left = OtherParts.Left

Button.MouseButton1Click:Connect(function()
	Left.Material = "Neon"
end)
 

This button is supposed to turn this union named "Left" material to Neon but it doesn't work, anything wrong with the script?