Factions error / HELP!

Any time I try to join a faction or anything like that (I am able to create factions, etc) but /f join gives me the An internal error message in game.



[11:46:05] [Server thread/INFO]: Vohqa issued server command: /f join test
[11:46:05] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing 'f join test' in com.massivecraft.massivecore.cmd.MassiveCoreBukkitCommand(f)
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:184) ~[craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at org.bukkit.craftbukkit.v1_7_R4.CraftServer.dispatchCommand(CraftServer.java:740) ~[craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.PlayerConnection.handleCommand(PlayerConnection.java:957) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.PlayerConnection.a(PlayerConnection.java:818) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.PacketPlayInChat.a(PacketPlayInChat.java:28) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.PacketPlayInChat.handle(PacketPlayInChat.java:47) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.NetworkManager.a(NetworkManager.java:157) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.ServerConnection.c(SourceFile:134) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.MinecraftServer.v(MinecraftServer.java:667) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.DedicatedServer.v(DedicatedServer.java:258) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.MinecraftServer.u(MinecraftServer.java:558) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:469) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
Caused by: java.lang.NoSuchMethodError: com.massivecraft.massivecore.cmd.arg.ARSenderEntity.getStartAny(Lcom/massivecraft/massivecore/store/SenderColl;)Lcom/massivecraft/massivecore/cmd/arg/ARSenderEntity;
at com.massivecraft.factions.cmd.arg.ARUPlayer.getStartAny(ARUPlayer.java:16) ~[?:?]
at com.massivecraft.factions.cmd.CmdFactionsJoin.perform(CmdFactionsJoin.java:48) ~[?:?]
at com.massivecraft.massivecore.cmd.MassiveCommand.execute(MassiveCommand.java:327) ~[?:?]
at com.massivecraft.massivecore.cmd.MassiveCommand.execute(MassiveCommand.java:306) ~[?:?]
at com.massivecraft.massivecore.cmd.MassiveCommand.execute(MassiveCommand.java:349) ~[?:?]
at com.massivecraft.massivecore.cmd.MassiveCoreBukkitCommand.execute(MassiveCoreBukkitCommand.java:67) ~[?:?]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:180) ~[craftbukkit.jar:git-Bukkit-1.7.9-R0.2-20-g0b2ed13-b3108jnks]
... 12 more