How come this script doesn't work? (Argument isnt valid)

function onPlayerEntered(player)
        player:WaitForDataReady()
        posx = player:LoadNumber(posx)
        wait(15)
        if posx ~= nil then
            local ScoreLoaded = player:LoadNumber(posx)
            local ScoreLoadedb = player:LoadNumber(posy)
            local ScoreLoadedc = player:LoadNumber(posz)
            local team = player:LoadString("team")
            player.TeamColor = team
            player.Character.Torso.Position = Vector3.new(ScoreLoaded, ScoreLoadedb, ScoreLoadedc)
        else
        end
        repeat
            posa =  player.Character.Torso.Position.x
            posb = player.Character.Torso.Position.y
            posc = player.Character.Torso.Position.z
            team = player.TeamColor
            print'Position Saved'
            wait(10)
        until nil
    end

    function onPlayerLeaving(player)
        player:SaveNumber(posx, posa)
        player:SaveNumber(posy, posb)
        player:SaveNumber(posz, posc)
        player:SaveString("team", team)
    end

    game.Players.PlayerAdded:connect(onPlayerEntered)
    game.Players.PlayerRemoving:connect(onPlayerLeaving)

basically i want to save the players position every like 10 seconds or so, and only load it when the player rejoins the game

I get an error saying argument isn't valid