How would I make a race checkpoint system?

--Spiyder1

local Part = script.Parent

while true do
	if workspace.Start.yes.Value == true
	then
		script.Parent.Transparency = .5
		script.Parent.lastheck.Value = true
		wait(.001)
	end
end

while true do
	if script.Parent.lastheck.Value == true
		then
			local function PlayerTouched(Part)
			print("hit")
			script.Parent.yeso.Value = true
			end
	
			wait(.001)
			Part.Touched:connect(PlayerTouched)
end

There's the code, I want to make the game see that a player hit a checkpoint so the player can continue the race normally (think vehicle legends racing) but the second checkpoint doesn't appear and I have no idea why. No output errors

(P.S. o at the end of the name stands for one)

Let me know if you have any questions about anything about the code! Thanks!