PingReply 1.5 issue

2013-03-15 22:49:28 [SEVERE] Could not pass event PlayerCommandPreprocessEvent to PingReply v1.1
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
    at net.minecraft.server.v1_5_R1.PlayerConnection.handleCommand(PlayerConnection.java:959)
    at net.minecraft.server.v1_5_R1.PlayerConnection.chat(PlayerConnection.java:885)
    at net.minecraft.server.v1_5_R1.PlayerConnection.a(PlayerConnection.java:840)
    at net.minecraft.server.v1_5_R1.Packet3Chat.handle(Packet3Chat.java:44)
    at net.minecraft.server.v1_5_R1.NetworkManager.b(NetworkManager.java:292)
    at net.minecraft.server.v1_5_R1.PlayerConnection.d(PlayerConnection.java:113)
    at net.minecraft.server.v1_5_R1.ServerConnection.b(SourceFile:35)
    at net.minecraft.server.v1_5_R1.DedicatedServerConnection.b(SourceFile:30)
    at net.minecraft.server.v1_5_R1.MinecraftServer.r(MinecraftServer.java:580)
    at net.minecraft.server.v1_5_R1.DedicatedServer.r(DedicatedServer.java:225)
    at net.minecraft.server.v1_5_R1.MinecraftServer.q(MinecraftServer.java:476)
    at net.minecraft.server.v1_5_R1.MinecraftServer.run(MinecraftServer.java:409)
    at net.minecraft.server.v1_5_R1.ThreadServerApplication.run(SourceFile:573)
Caused by: org.bukkit.command.CommandException: Unhandled exception executing command 'ping1' in plugin PingReply v1.1
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
    at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:186)
    at org.bukkit.craftbukkit.v1_5_R1.CraftServer.dispatchCommand(CraftServer.java:514)
    at org.bukkit.craftbukkit.v1_5_R1.entity.CraftPlayer.performCommand(CraftPlayer.java:238)
    at com.tschagg.PingReply.tschaggplugin_listener.onPlayerCommandPreprocess(tschaggplugin_listener.java:23)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
    ... 16 more
Caused by: java.lang.NoClassDefFoundError: org/bukkit/craftbukkit/v1_4_R1/entity/CraftPlayer
    at com.tschagg.PingReply.tschaggplugin_main.getPing(tschaggplugin_main.java:104)
    at com.tschagg.PingReply.tschaggplugin_main.onCommand(tschaggplugin_main.java:66)
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
    ... 25 more
Caused by: java.lang.ClassNotFoundException: org.bukkit.craftbukkit.v1_4_R1.entity.CraftPlayer
    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(ClassLoader.java:423)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    ... 28 more
2013-03-15 22:49:28 [INFO] [CommandLog] Player 'zaza7' used command: '/ping'