Sneaker 1.2 error during plugin reload:

01:21:08 [SEVERE] Could not load 'plugins/Sneaker-1.2.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: com/Tstop/sneaker/Sneaker : Unsupported major.minor version 51.0
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:184)
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305)
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
        at org.bukkit.craftbukkit.v1_4_R1.CraftServer.loadPlugins(CraftServer.java:239)
        at org.bukkit.craftbukkit.v1_4_R1.CraftServer.reload(CraftServer.java:594)
        at org.bukkit.Bukkit.reload(Bukkit.java:184)
        at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:23)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:186)
        at org.bukkit.craftbukkit.v1_4_R1.CraftServer.dispatchCommand(CraftServer.java:514)
        at org.bukkit.craftbukkit.v1_4_R1.CraftServer.dispatchServerCommand(CraftServer.java:506)
        at net.minecraft.server.v1_4_R1.DedicatedServer.al(DedicatedServer.java:260)
        at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:225)
        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.UnsupportedClassVersionError: com/Tstop/sneaker/Sneaker : Unsupported major.minor version 51.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:80)
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:247)
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:173)
        ... 14 more




>version
01:26:12 [INFO] This server is running CraftBukkit version git-Bukkit-1.4.7-R1.0-b2624jnks (MC: 1.4.7) (Implementing API version 1.4.7-R1.0)