My script not working no errors but only the enum material error?

So when I press w or s it does nothing and the enum material code won't work It's in a normal script inside the cars reverse lights mesh Code:

while true do
	ReverseLights = Enum.KeyCode.S
	ReverseLights2 = Enum.KeyCode.W
	if ReverseLights then script.Parent.Transparency = 0 and script.Parent.Material = Enum.Material
		
	end
	if ReverseLights2 then script.Parent.Transparency = 0.5 and script.Parent.Material = Enum.Material.SmoothPlastic
		
	end
	script.Parent.Transparency = 0.20
	wait(.20)
	script.Parent.Transparency = 0.20
		wait(.20)
		end

You need to choose a material in the enum like Neon, SmoothPlastic, Brick and other stuff.