org.bukkit.command.CommandException: Unhandled exception executing command 'd' in plugin VoxelSniper v5.168.3-SNAPSHOT-jnks187
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:186)
at org.bukkit.craftbukkit.v1_4_R1.CraftServer.dispatchCommand(CraftServer.java:514)
at net.minecraft.server.v1_4_R1.PlayerConnection.handleCommand(PlayerConnection.java:979)
at net.minecraft.server.v1_4_R1.PlayerConnection.chat(PlayerConnection.java:897)
at net.minecraft.server.v1_4_R1.PlayerConnection.a(PlayerConnection.java:852)
at net.minecraft.server.v1_4_R1.Packet3Chat.handle(Packet3Chat.java:44)
at net.minecraft.server.v1_4_R1.NetworkManager.b(NetworkManager.java:290)
at net.minecraft.server.v1_4_R1.PlayerConnection.d(PlayerConnection.java:112)
at net.minecraft.server.v1_4_R1.ServerConnection.b(SourceFile:39)
at net.minecraft.server.v1_4_R1.DedicatedServerConnection.b(SourceFile:30)
at net.minecraft.server.v1_4_R1.MinecraftServer.r(MinecraftServer.java:598)
at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:224)
at net.minecraft.server.v1_4_R1.MinecraftServer.q(MinecraftServer.java:494)
at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:427)
at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.NoClassDefFoundError: net/minecraft/server/v1_4_6/EntityLiving
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.getConstructor(Unknown Source)
at com.thevoxelbox.voxelsniper.SniperBrushes.getBrush(SniperBrushes.java:287)
at com.thevoxelbox.voxelsniper.SniperBrushes.getSniperBrushes(SniperBrushes.java:240)
at com.thevoxelbox.voxelsniper.Sniper.(Sniper.java:96)
at com.thevoxelbox.voxelsniper.SniperPermissionHelper.getSniperInstance(SniperPermissionHelper.java:28)
at com.thevoxelbox.voxelsniper.VoxelSniperListener.commandSniperD(VoxelSniperListener.java:219)
at com.thevoxelbox.voxelsniper.VoxelSniperListener.onCommand(VoxelSniperListener.java:46)
at com.thevoxelbox.voxelsniper.VoxelSniper.onCommand(VoxelSniper.java:234)
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
... 15 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_4_6.EntityLiving
at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:70)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 27 more
2013-01-20 21:52:40 [INFO] eclaro001 issued server command: /d
2013-01-20 21:52:40 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'd' in plugin VoxelSniper v5.168.3-SNAPSHOT-jnks187
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:186)
at org.bukkit.craftbukkit.v1_4_R1.CraftServer.dispatchCommand(CraftServer.java:514)
at net.minecraft.server.v1_4_R1.PlayerConnection.handleCommand(PlayerConnection.java:979)
at net.minecraft.server.v1_4_R1.PlayerConnection.chat(PlayerConnection.java:897)
at net.minecraft.server.v1_4_R1.PlayerConnection.a(PlayerConnection.java:852)
at net.minecraft.server.v1_4_R1.Packet3Chat.handle(Packet3Chat.java:44)
at net.minecraft.server.v1_4_R1.NetworkManager.b(NetworkManager.java:290)
at net.minecraft.server.v1_4_R1.PlayerConnection.d(PlayerConnection.java:112)
at net.minecraft.server.v1_4_R1.ServerConnection.b(SourceFile:39)
at net.minecraft.server.v1_4_R1.DedicatedServerConnection.b(SourceFile:30)
at net.minecraft.server.v1_4_R1.MinecraftServer.r(MinecraftServer.java:598)
at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:224)
at net.minecraft.server.v1_4_R1.MinecraftServer.q(MinecraftServer.java:494)
at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:427)
at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.NoClassDefFoundError: net/minecraft/server/v1_4_6/EntityLiving
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.getConstructor(Unknown Source)
at com.thevoxelbox.voxelsniper.SniperBrushes.getBrush(SniperBrushes.java:287)
at com.thevoxelbox.voxelsniper.SniperBrushes.getSniperBrushes(SniperBrushes.java:240)
at com.thevoxelbox.voxelsniper.Sniper.(Sniper.java:96)
at com.thevoxelbox.voxelsniper.SniperPermissionHelper.getSniperInstance(SniperPermissionHelper.java:28)
at com.thevoxelbox.voxelsniper.VoxelSniperListener.commandSniperD(VoxelSniperListener.java:219)
at com.thevoxelbox.voxelsniper.VoxelSniperListener.onCommand(VoxelSniperListener.java:46)
at com.thevoxelbox.voxelsniper.VoxelSniper.onCommand(VoxelSniper.java:234)
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
... 15 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_4_6.EntityLiving
at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:70)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 27 more

Wrong version of VoxelSniper. Get the latest from http://ci.thevoxelbox.com/