Why do monsters spawn?

I have two worlds on my server, and as far as i'm sure, only the newest one has monsters. I haven't checked the first one though. This is my server thing:

Code:

#Minecraft server properties
#Sat Jul 16 14:02:15 EST 2011
level-name=Shadek
allow-nether=true
view-distance=10
spawn-monsters=false
online-mode=false
spawn-animals=true
max-players=20
server-ip=5.57.144.34
pvp=true
level-seed=
server-port=25565
allow-flight=true
white-list=false

I downloaded Dungeon Builder, and built another world specifically for that. So why are monsters appearing?

 

You need to change the setting on your multiworld plugin. Each world needs to be configured to how you want it to run.

 

How do I do that?

 

Read about the plugin, most have instructions