How to save leaderstats?

Hello!

I'm making a game, and I want people's KOs to save through its alpha stages.

I've tried to write this code multiple times, and it never works.

I have the basic leaderstats script, except I changed "KOs" and "Wipeouts" to "Kills" and "Deaths".

It's supposed to keep a running value of kills and deaths; if you leave the game at 2 kills, you'll come back with 2, if you leave with 4, next time you come back, you'll have 4.

Here's the saving script:

local KOStore = game:GetService("DataStoreService"):GetDataStore("KO")
local WOStore = game:GetService("DataStoreService"):GetDataStore("WO")

game.Players.PlayerAdded:connect(function(plr)
	
	plr:WaitForChild("leaderstats")
	plr.leaderstats:WaitForChild("Kills")
	plr.leaderstats:WaitForChild("Deaths")
	
	local KOkey,WOkey = "user_"..plr.userId.."KO","user_"..plr.userId.."WO"
	
	plr.leaderstats.Kills.Value,plr.leaderstats.Deaths.Value = KOStore:GetAsync(KOkey),WOStore:GetAsync(WOkey)
		
end)

game.Players.PlayerRemoving:connect(function(plr)
	
	local KOkey,WOkey = "user_"..plr.userId.."KO","user_"..plr.userId.."WO"
	
	KOStore:UpdateAsync(KOkey,function(oldValue)
		if oldValue then
			return (oldValue + plr.leaderstats.Kills.Value)
		else
			return (plr.leaderstats.Kills.Value)
		end
	end)
	
end)

I've tested this both on studio servers and actual servers, and it doesn't work on either.