script wont destroy sound at night time?

When it's night, this script is supposed to destroy this sound that is playing in the workspace, but it doesnt. It places the sound in just fine, but wont destroy it. This is really annoying me. Any help?

while true do
	wait()
	if game.Lighting.ClockTime >= 7 and game.Lighting.ClockTime <= 17 then
		if workspace:FindFirstChild("Seagull") == nil then
			local sound = script.Seagull:Clone()
			sound.Parent = workspace
			sound:Play()
		end
	if game.Lighting.ClockTime <= 6 and game.Lighting.ClockTime >= 18 then
		if workspace:FindFirstChild("Seagull") ~= nil then
			workspace.Seagull:Destroy()
			end
		end
	end
end

thanks for reading