Falling block bug

Hello,

Im making a balloon plugin, And I have a bug that I can't fix,
The plugin spawns a invinsible bat on the player's location with a falling block on the bat his head, But I have the problem that sometimes the block breakes itself!
How to fix this? This is my code

Code:

 Player player = (Player)sender;
            Location location = player.getEyeLocation().add(0.0D, 2.0D, 0.0D);
            FallingBlock fallingBlock = player.getWorld().spawnFallingBlock(location, Material.STAINED_CLAY, (byte) 15);
            Bat bat = (Bat)player.getWorld().spawn(location, Bat.class);
            bat.setPassenger(fallingBlock);
            bat.setLeashHolder(player);
            player.setPassenger(bat);
            bat.addPotionEffect(new PotionEffect(PotionEffectType.INVISIBILITY, 100000, 100000));

 

Wrong forum. please put under Plugin Development

 

Moved thread to Plugin Development. Plugin Requests is meant more for asking people to make plugins for you, not for coding help.

Edit: Oops, should've looked before I moved it. Already a dupe here: http://forums.bukkit.org/threads/falling-block-bug.307153/#post-2771350 So....gonna lock this one.