HELP!

[2016-02-07 14:14:59,632-0500] [Server thread/INFO]: InvertedTNT issued server command: /manlaod
[2016-02-07 14:15:01,332-0500] [Server thread/INFO]: InvertedTNT issued server command: /manload
[2016-02-07 14:15:01,332-0500] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'manload' in plugin GroupManager v2.1.31 (Phoenix)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) ~[spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:641) ~[spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.PlayerConnection.handleCommand(PlayerConnection.java:1162) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:997) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:45) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:1) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_66]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_66]
        at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_66]
Caused by: java.lang.NullPointerException
        at org.anjocaido.groupmanager.GroupManager.onCommand(GroupManager.java:420) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[spigot-1.8.8.jar:git-Spigot-db6de12-07c3001]
        ... 15 more
[2016-02-07 14:15:24,159-0500] [Server thread/INFO]: CONSOLE issued server command: /baltop
[2016-02-07 14:15:24,168-0500] [Server thread/INFO]: ?cInvertedTNT ?4was denied access to command.
[2016-02-07 14:15:24,172-0500] [Server thread/INFO]: CONSOLE issued server command: /baltop
[2016-02-07 14:15:24,172-0500] [Server thread/INFO]: ?cInvertedTNT ?4was denied access to command.
[2016-02-07 14:15:27,858-0500] [Server thread/INFO]: InvertedTNT lost connection: Disconnected
[2016-02-07 14:15:27,871-0500] [Server thread/INFO]: InvertedTNT left the game!