Need help! Respawning a Chest + Inventory

Hello Minecraft Dudes/Mates/Dudettes/Matesses!
I'm trying to create a plugin for loot chests, that gives the player a random item from a chest when he right-clicks it, and then disappears for a time.

But I'm getting problems right now. I have this code:

Code:java

 public void RespawnChest(final Chest chest, final Location loc){
 
final Inventory inv = chest.getBlockInventory();
Bukkit.getServer().getScheduler().scheduleSyncDelayedTask(Bukkit.getServer().getPluginManager().getPlugin("DungeonsAndEnderdragons"), new Runnable(){
 
int time = 100;
Location l = loc;
 
public void run(){
 
if (loc.getBlock().getType() != Material.AIR){
loc.getBlock().setType(Material.AIR);
}
 
if (time >= 0){
loc.getBlock().setType(Material.CHEST);
Chest c = (Chest) loc.getBlock().getState();
for (ItemStack i : inv.getContents()){
c.getInventory().addItem(i);
}
return;
}
 
time--;
 
Bukkit.getServer().getScheduler().scheduleSyncDelayedTask(Bukkit.getServer().getPluginManager().getPlugin("DungeonsAndEnderdragons"), this, 20L);
 
}
 
});
 
}

But I'm getting a IllegalPluginAccessException at this line (first time it comes):

Code:java

Bukkit.getServer().getScheduler().scheduleSyncDelayedTask(Bukkit.getServer().getPluginManager().getPlugin("DungeonsAndEnderdragons"), this, 20L);

The Name of the Plugin is DungeonsAndEnderdragons, I controlled it several times. I already changed

Code:java

Bukkit.getServer().getScheduler().scheduleSyncDelayedTask(Bukkit.getServer().getPluginManager().getPlugin("DungeonsAndEnderdragons")

to "this", but the error keeps there. The name of the Plugin must be right. I'm pretty sure about that.

So, do you have an idea why it throws the exception?

Gabum