Problem/Bug Citizens Not Working

I am trying to use Citizens on my minecraft server. Everytime I try to run the NPC command it tells me an Internal Error has occurred. How do I fix that?

This is the Log when I ran it:

Code:

[21:26:36] [Server thread/INFO]: icepik00 issued server command: /npc
[21:26:36] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Cannot execute command 'npc' in plugin Citizens v2.0.24-SNAPSHOT (build 1605) - plugin is disabled.
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:37) ~[Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:149) ~[Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at org.bukkit.craftbukkit.v1_15_R1.CraftServer.dispatchCommand(CraftServer.java:723) ~[Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.PlayerConnection.handleCommand(PlayerConnection.java:1658) ~[Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.PlayerConnection.a(PlayerConnection.java:1498) ~[Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.PacketPlayInChat.a(PacketPlayInChat.java:47) ~[Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.PacketPlayInChat.a(PacketPlayInChat.java:1) ~[Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.PlayerConnectionUtils.lambda$0(PlayerConnectionUtils.java:19) ~[Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.TickTask.run(SourceFile:18) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeTask(SourceFile:144) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeNext(SourceFile:118) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.MinecraftServer.ba(MinecraftServer.java:918) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.MinecraftServer.executeNext(MinecraftServer.java:911) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeAll(SourceFile:103) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.MinecraftServer.sleepForTick(MinecraftServer.java:894) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:828) [Spigot_Latest.jar:git-Spigot-2f5d615-d07a78b]
    at java.lang.Thread.run(Thread.java:748) [?:1.8.0_211]

 

your using a version of the plugin that's ether outdated or incompatible with you Minecraft version, I had the same issue the other day, check what version of Minecraft your playing on and download the plugin again