SVL initial error

2013-06-21 16:10:10 [INFO] [SimpleVoteListener] Enabling SimpleVoteListener v2.6
2013-06-21 16:10:10 [SEVERE] Error occurred while enabling SimpleVoteListener v2.6 (Is it up to date?)
java.lang.UnsupportedClassVersionError: me/puyttre/svl/JoinEvent : 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.JavaPluginLoader.getClassByName0(JavaPluginLoader.java:300)
	at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:76)
	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 me.puyttre.svl.SimpleVoteListener.onEnable(SimpleVoteListener.java:25)
	at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:217)
	at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:457)
	at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:381)
	at org.bukkit.craftbukkit.v1_5_R3.CraftServer.loadPlugin(CraftServer.java:282)
	at org.bukkit.craftbukkit.v1_5_R3.CraftServer.enablePlugins(CraftServer.java:264)
	at net.minecraft.server.v1_5_R3.MinecraftServer.j(MinecraftServer.java:304)
	at net.minecraft.server.v1_5_R3.MinecraftServer.e(MinecraftServer.java:283)
	at net.minecraft.server.v1_5_R3.MinecraftServer.a(MinecraftServer.java:243)
	at net.minecraft.server.v1_5_R3.DedicatedServer.init(DedicatedServer.java:151)
	at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java:382)
	at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:573)