GroupManager HELP!

Here is my error, anyone please?
18:09:02 [INFO] [GroupManager] Enabling GroupManager v1.9 (2.9.1) (Phoenix)
18:09:02 [SEVERE] java.lang.IllegalArgumentException: Invalid node type, or bad
indentation in file: plugins\GroupManager\worlds\world\groups.yml
18:09:02 [SEVERE] at org.anjocaido.groupmanager.dataholder.WorldDataHolder
.loadGroups(WorldDataHolder.java:552)
18:09:02 [SEVERE] at org.anjocaido.groupmanager.dataholder.WorldDataHolder
.loadGroups(WorldDataHolder.java:380)
18:09:02 [SEVERE] at org.anjocaido.groupmanager.dataholder.worlds.WorldsHo
lder.loadWorld(WorldsHolder.java:586)
18:09:02 [SEVERE] at org.anjocaido.groupmanager.dataholder.worlds.WorldsHo
lder.loadWorld(WorldsHolder.java:549)
18:09:02 [SEVERE] at org.anjocaido.groupmanager.dataholder.worlds.WorldsHo
lder.initialWorldLoading(WorldsHolder.java:79)
18:09:02 [SEVERE] at org.anjocaido.groupmanager.dataholder.worlds.WorldsHo
lder.initialLoad(WorldsHolder.java:70)
18:09:02 [SEVERE] at org.anjocaido.groupmanager.dataholder.worlds.WorldsHo
lder.<init>(WorldsHolder.java:62)
18:09:02 [SEVERE] at org.anjocaido.groupmanager.GroupManager.onEnable(Grou
pManager.java:131)
18:09:02 [SEVERE] at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlug
in.java:215)
18:09:02 [SEVERE] at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(
JavaPluginLoader.java:337)
18:09:02 [SEVERE] at org.bukkit.plugin.SimplePluginManager.enablePlugin(Si
mplePluginManager.java:381)
18:09:02 [SEVERE] at org.bukkit.craftbukkit.CraftServer.loadPlugin(CraftSe
rver.java:256)
18:09:02 [SEVERE] at org.bukkit.craftbukkit.CraftServer.enablePlugins(Craf
tServer.java:238)
18:09:02 [SEVERE] at net.minecraft.server.MinecraftServer.t(MinecraftServe
r.java:381)
18:09:02 [SEVERE] at net.minecraft.server.MinecraftServer.a(MinecraftServe
r.java:368)
18:09:02 [SEVERE] at net.minecraft.server.MinecraftServer.init(MinecraftSe
rver.java:197)
18:09:02 [SEVERE] at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:432)
18:09:02 [SEVERE] at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:492)
18:09:02 [SEVERE] Error occurred while enabling GroupManager v1.9 (2.9.1) (Phoen
ix) (Is it up to date?)
java.lang.IllegalArgumentException: Your plugins\GroupManager\worlds\world\group
s.yml file is invalid. See console for details.
at org.anjocaido.groupmanager.dataholder.WorldDataHolder.loadGroups(Worl
dDataHolder.java:556)
at org.anjocaido.groupmanager.dataholder.WorldDataHolder.loadGroups(Worl
dDataHolder.java:380)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.loadWorld(W
orldsHolder.java:586)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.loadWorld(W
orldsHolder.java:549)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.initialWorl
dLoading(WorldsHolder.java:79)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.initialLoad
(WorldsHolder.java:70)
at org.anjocaido.groupmanager.dataholder.worlds.WorldsHolder.<init>(Worl
dsHolder.java:62)
at org.anjocaido.groupmanager.GroupManager.onEnable(GroupManager.java:13
1)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:215)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader
.java:337)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManage
r.java:381)
at org.bukkit.craftbukkit.CraftServer.loadPlugin(CraftServer.java:256)
at org.bukkit.craftbukkit.CraftServer.enablePlugins(CraftServer.java:238
)
at net.minecraft.server.MinecraftServer.t(MinecraftServer.java:381)
at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:368)
at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:197)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:432)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)