erreur

[22:46:02] Flubox: 2014-07-29 22:43:14 [SEVERE] Could not load 'plugins/SetBlock.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: fr/guenezan/bukkit/setBlock/SetBlock : Unsupported major.minor version 52.0
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:184)
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:306)
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
        at org.bukkit.craftbukkit.v1_6_R3.CraftServer.loadPlugins(CraftServer.java:245)
        at net.minecraft.server.v1_6_R3.DedicatedServer.init(DedicatedServer.java:118)
        at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:399)
        at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
Caused by: java.lang.UnsupportedClassVersionError: fr/guenezan/bukkit/setBlock/SetBlock : Unsupported major.minor version 52.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:80)
[22:46:18] Flubox:  at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:270)
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:173)
        ... 6 more