Flashing lights not working, how do I make them flash?

light = script.Parent.SpotLight

while true do
light.Brightness = 19
wait (1)
light.Brightness = 0
end

This isn't working for me and it's quite frustrating! Please can someone help me.

It should work. It can only work with one light unless you indicate more lights with different names.

local light = script.Parent.SpotLight

while true do
light.Brightness = 19
wait(1)
light.Brightness = 0
wait(1)
end