Cannot store Array in DataStore?

The question title is what the output id reading. "Cannot store Array in DataStore". How can I fix this?

It was working so far with Exp, Rank, and RankVal, but now after adding RunVal, WalkVal, and Cash it does not work.

Here's my code so far:

local dss = game:GetService("DataStoreService"):GetDataStore("Data") -- Give it a name.

game.Players.PlayerAdded:connect(function(plr)

    local UniqueKey = 'id-'..plr.UserId



    local stats = Instance.new("Folder", plr)
    stats.Name = "leaderstats"

    local rank = Instance.new("StringValue", stats)
    rank.Name = "Rank" 
    rank.Value = "Newbie"

    local val = Instance.new("IntValue", stats)
    val.Name = "RankVal"
    val.Value = 1

    local exp1 = Instance.new("IntValue", stats)
    exp1.Name = "Exp"
    exp1.Value = 0

	local run = Instance.new("IntValue", plr)
	run.Name = "RunVal"
	run.Value = 50
	
	local walk = Instance.new("IntValue", plr)
	walk.Name = "WalkVal"
	walk.Value = 35
	
	local cash = Instance.new("IntValue", stats)
	cash.Name = "Cash"
	cash.Value = 0



    local GetSaved = dss:GetAsync(UniqueKey)
    if GetSaved then
	    rank.Value = GetSaved[1]
	    val.Value = GetSaved[2]
	    exp1.Value = GetSaved[3]
		run.Value = GetSaved[4]
		walk.Value = GetSaved[5]
		cash.Value = GetSaved[6]
    else
        local toSave = {rank.Value, val.Value, exp1.Value, run.Value, walk.Value, cash.Value}
        dss:SetAsync(UniqueKey, toSave)
    end
	game.ReplicatedStorage.Event:FireAllClients(plr.Name, val.Value);
	val.Changed:connect(function()
		game.ReplicatedStorage.Event:FireAllClients(plr.Name, val.Value);
	end)
end)

game.Players.PlayerRemoving:connect(function(plr)

local UniqueKey = 'id-'..plr.UserId
local d = plr.leaderstats
local savetable = {d.Rank.Value, d.RankVal.Value, d.Exp.Value, plr.RunVal, plr.WalkVal, d.Cash}   -- A table to hold/save all the values.

dss:SetAsync(UniqueKey,savetable)
end)