Solved Problem with Scoreboard

Hi! I've a problem with the scoreboard on a plugin i'm working on.
Here's the server log:

Code:

[...]
Caused by: java.lang.IllegalStateException: Cannot set scoreboard for invalid CraftPlayer
    at org.bukkit.craftbukkit.v1_6_R2.entity.CraftPlayer.setScoreboard(CraftPlayer.java:1011)
    at com.gmail.sifacemarco.godscraft.gods.Follower.showScoreboard(Follower.java:43)
    at com.gmail.sifacemarco.godscraft.gods.GodManager.showScoreboard(GodManager.java:350)
    at com.gmail.sifacemarco.godscraft.commhandler.CommandHandler.onCommand(CommandHandler.java:138)
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
    ... 15 more

And this is the code which manages the scoreboard:

Code:java

public class Follower
{
    private Player p;
    private int rep;
    private God god;
    private GregorianCalendar lastPrayed;
    private GregorianCalendar lastHealed;
    private Scoreboard s;
    public Follower(Player p, int rep, God god, GregorianCalendar lastPrayed,GregorianCalendar lastHealed)
    {
        this.p=p;
        this.rep=rep;
        this.god=god;
        this.lastPrayed=lastPrayed;
        this.lastHealed=lastHealed;
        updateScore();
    }
    public void updateScore()
    {
        s=Bukkit.getScoreboardManager().getNewScoreboard();
        s.registerNewObjective("Reputazione", "dummy");
        Objective o=s.getObjective("Reputazione");
        o.setDisplaySlot(DisplaySlot.SIDEBAR);
        Score r=o.getScore(p);
        r.setScore(Utility.getLevel(rep));
        p.setScoreboard(s);
    }
    public void showScoreboard()
    {
        p.setScoreboard(s);
    }
    public void hideScoreboard()
    {
        p.setScoreboard(Bukkit.getScoreboardManager().getNewScoreboard());
    }
    [...]
}

Basically: when a player joins the server, under certain conditions, a Follower object is created. At the first login it's all ok, the scoreboard is shown correctly, and so on. But, if the player log out and then log back again, that exception occurs, and I've to stop the server to get things to work again. I'm not getting something, or it's a known problem? Thank you! (BTW sorry for my bad english, i'm not a native speaker...)

 

Moved to correct section.

 

Whoops, sorry :/

 

Elsifo92

You need to save it in a config.

 

I solved it.
For anyone having the same problem: you don't have to delete the reference to the scoreboard, keep it saved in a HashMap for example. Then, when the player logs again, just set that scoreboard. Thanks anyway PropGamer for the answer!