Making this leaderboard work?

Hey. I'm working on a high score system for my game. It's the final feature and I really need it done. So far, I have this script, and it works perfectly to add players to the leader board, however every now and then it fails to update the scores. There is never any output and I can't work out why it doesn't work. One thing I have found is that if they player has already set a score, and there is a higher ranking player, that's when it fails to update. Please help!

local scores = script:GetChildren()
local DataStore = game:GetService("DataStoreService"):GetDataStore("HighScore_V7")

for i = 1,#scores do
	local value = scores[i].Name
	local setter = value.."Setter"
	scores[i].Value = DataStore:GetAsync(value)
	if DataStore:GetAsync(setter) ~= nil then
		scores[i].Setter.Value = DataStore:GetAsync(setter)
	end
end

game.Players.PlayerAdded:connect(function(player)
	local highScore = player:FindFirstChild("highScore")
	if highScore then
		highScore.Changed:connect(function(val)
			updateScores(player.Name,highScore.Value)
		end)
	end
end)

function updateScores(player,val)
	for i = 1,#scores do
		if val >= scores[i].Value then
			if scores[i].Setter.Value == player then
				scores[i].Value = val
				for b = 1,#scores do
					if scores[b].Setter.Value == player then
						if b ~= i then
							local tempVal = scores[b].Value
							local tempSetter = scores[b].Setter.Value
							scores[b].Value = 0
							scores[b].Setter.Value = ""
							moveUp(b,tempSetter,tempVal)
						end
					end
				end
				break
			else
				local good = true
				for b = 1,#scores do
					if scores[b].Setter.Value == player then
						good = false
					end
				end
				if good == true then
					moveBack(i,player,val)
				end
				break
			end
		end
	end
end

function moveBack(enterPos,setter,val)
	local prevVal = val
	local prevValTemp
	local prevSetter = setter
	local prevSetterTemp
	for i = enterPos,#scores do
		prevValTemp = scores[i].Value
		prevSetterTemp = scores[i].Setter.Value
		scores[i].Value  = prevVal
		scores[i].Setter.Value = prevSetter
		prevVal = prevValTemp
		prevSetter = prevSetterTemp
	end
end

function moveUp(enterPos,setter,val)
	local prevVal = val
	local prevValTemp
	local prevSetter = setter
	local prevSetterTemp
	for i = enterPos,#scores do
		local b = #scores - i
		if scores[b] then
			prevValTemp = scores[i].Value
			prevSetterTemp = scores[i].Setter.Value
			scores[i].Value  = prevVal
			scores[i].Setter.Value = prevSetter
			prevVal = prevValTemp
			prevSetter = prevSetterTemp
		end
	end
end

function mashUp(newScores)
	for i = 1,#newScores do
		updateScores(newScores[i].Setter.Value,newScores[i].Value)
	end
end

game.OnClose = function()
	local newScores = script.Parent.newScores:GetChildren()
	for i = 1,#scores do
		local val = scores[i].Name
		local setter = val.."Setter"
		newScores[i].Value = DataStore:GetAsync(val)
		newScores[i].Setter.Value = DataStore:GetAsync(setter)		
	end
	wait(1)
	for i = 1,#scores do
		local value = scores[i].Name
		local setter = value.."Setter"
		DataStore:SetAsync(value,scores[i].Value)
		DataStore:SetAsync(setter,scores[i].Setter.Value)
	end
end

Sorry it's a long script, but it's all necessary... I think...