storing or loading from data store not working, why?

i am trying to save player data to data store using a script i found and modified The original script is from this website

I modified it so that it would store three values Experience as IntValue Rank as StringValue Bucks as IntValue

before i modified the script it worked but now it doesn't work anymore, i wonder have i referenced the data i want to store correctly?

my modified script is beloew

-- Data Storage
local DataStoreService = game:GetService("DataStoreService")

local playerData = DataStoreService:GetDataStore("PlayerData")



local function onPlayerJoin(player)  -- Runs when players join

	local leaderstats = Instance.new("Folder")  --Sets up leaderstats folder

	leaderstats.Name = "leaderstats"

	leaderstats.Parent = player

	local bucks = Instance.new("IntValue") --Sets up value for leaderstats

	bucks.Name = "Bucks"

	bucks.Parent = leaderstats

	local exp = Instance.new("IntValue") --Sets up value for leaderstats

	exp.Name = "Experience"

	exp.Parent = leaderstats
	
	
	local rank = Instance.new("StringValue") --Sets up value for leaderstats

	rank.Name = "Rank"

	rank.Parent = leaderstats



	local playerUserId = "Player_" .. player.UserId  --Gets player ID

	local data = playerData:GetAsync(playerUserId)  --Checks if player has stored data

	if data then

		bucks.Value = data['Bucks']

		exp.Value = data['Experience']
		
		rank.Value = data['Rank']

	else

		-- Data store is working, but no current data for this player

		bucks.Value = 50

		exp.Value = 50
		
		rank.Value = "Rec"

	end

end



local function create_table(player)

	local player_stats = {}

	for _, stat in pairs(player.leaderstats:GetChildren()) do

		player_stats[stat.Name] = stat.Value

	end

	return player_stats

end



local function onPlayerExit(player)  --Runs when players exit



	local player_stats = create_table(player)

	local success, err = pcall(function()

		local playerUserId = "Player_" .. player.UserId

		playerData:SetAsync(playerUserId, player_stats) --Saves player data

	end)



	if not success then

		warn('Could not save data!')

	end

end



game.Players.PlayerAdded:Connect(onPlayerJoin)

game.Players.PlayerRemoving:Connect(onPlayerExit)