Sending Packet causing error?

Hey guys today I'm experiencing a slight problem. I'm pretty new to Packets, but I seem to keep getting an error, not exactly sure why. I'll post my stack trace at the bottom, aswell as my code.
Packet Code:

Code:

    Bukkit.getServer().getScheduler().scheduleAsyncRepeatingTask(plugin, new Runnable(){
                            public void run(){
                                for(Entity nb : p.getNearbyEntities(50, 50, 50)){
                                    if(nb instanceof Snowball){
                                    if(plugin.snowball.contains(nb)){
                                        PacketPlayOutWorldEvent packet = new PacketPlayOutWorldEvent(Effect.STEP_SOUND.getId(), nb.getLocation().getBlockX(), nb.getLocation().getBlockY(), nb.getLocation().getBlockZ(), 0, false);
                                            for (Player pl : Bukkit.getServer().getOnlinePlayers()){
                                            PlayerConnection pc = ((CraftPlayer) pl.getPlayer()).getHandle().playerConnection;
                                            if(pc == null) continue;
                                            pc.sendPacket(packet);
                                        }
                                       
                                    }
                                }
                                }
                            }
                        }, 0, 1);

Stack trace:

Code:

[02:30:18] [Server thread/ERROR]: Could not pass event ProjectileLaunchEvent to lKits v1.0
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:320) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:486) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:471) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.craftbukkit.v1_7_R1.event.CraftEventFactory.callProjectileLaunchEvent(CraftEventFactory.java:603) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.World.addEntity(World.java:904) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.World.addEntity(World.java:871) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.craftbukkit.v1_7_R1.entity.CraftLivingEntity.launchProjectile(CraftLivingEntity.java:342) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.craftbukkit.v1_7_R1.entity.CraftLivingEntity.launchProjectile(CraftLivingEntity.java:298) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at me.TommyRaids.lEvents.Events.onPrisoner(Events.java:241) [lKits.jar:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.6.0_21]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.6.0_21]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.6.0_21]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.6.0_21]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:318) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:486) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:471) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.craftbukkit.v1_7_R1.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:195) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.craftbukkit.v1_7_R1.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:165) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.PlayerConnection.a(PlayerConnection.java:604) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.PacketPlayInBlockPlace.a(SourceFile:60) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.PacketPlayInBlockPlace.handle(SourceFile:9) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.NetworkManager.a(NetworkManager.java:146) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.ServerConnection.c(SourceFile:134) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:655) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:250) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:545) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:457) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
Caused by: java.lang.NoClassDefFoundError: net/minecraft/server/v1_7_R4/Packet
    at me.TommyRaids.lEvents.Events.particlesFollow(Events.java:260) ~[?:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.6.0_21]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.6.0_21]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.6.0_21]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.6.0_21]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:318) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    ... 29 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_7_R4.Packet
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:67) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:62) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.6.0_21]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.6.0_21]
    at me.TommyRaids.lEvents.Events.particlesFollow(Events.java:260) ~[?:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.6.0_21]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.6.0_21]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.6.0_21]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.6.0_21]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:318) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    ... 29 more

 

@Tommy Raids

Erm, your issue is quite simple.

You're violating the thread safety of the server. I don't understand why people feel the need to make EVERYTHING ASYNC HURRRDURR. Frankly, it's rather annoying.

Also, you're trying to access a class that doesn't exist on the class path, it says it right there: java.lang.ClassNotFoundException

 

@mythbusterma
Erm, I'm using NMS 1.7.4, I tried importing other versions. Not sure what's going on. And for the async, what would you suggest for an alternative?..

 

@Tommy Raids

Sync, just don't put an "a" in it.

You're using the wrong version of the server to be using that packet anyway.

 

Alright. @mythbusterma I'll try updating to 1.7.10, thanks for helping.

@mythbusterma How would I update my NMS? Since Bukkit dls are no longer available, what should I do? :3

EDIT by Moderator: merged posts, please use the edit button instead of double posting.