Bukkit

What steps will reproduce the problem?
1. built the arena in a world with multiverse
2. joined the arena
3. wave 1 which was meant to have 4 mobs only spawns 1 and the console shows this error http://pastebin.com/Tbd06r7h

What is the expected output? What do you see instead?
1 mob spawned instead of 4.

What version of the plugin are you using?
v1.1.4.1

Do you have an error log of what happened?
http://pastebin.com/Tbd06r7h

Please provide any additional information below.
the arena built in the normal world that was not generated by multiverse was fine

"the arena built in the normal world that was not generated by multiverse was fine"
hmm... No problems there what so ever? Either I'm getting the world wrong somehow or bukkit fucked up the spawning... Gonna take a look.

See comments on main page. Should be fixed in the next version, but I'm gonna leave this open if this still persists.