X54321

I'm trying to set up a Tekkit server, but when I open the launcher it keeps saying : Failed to load mod from "mod_IC2AdvancedMachines.class" 2012-04-01 18:07:28 [FINER] THROW java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_IC2AdvancedMachines : Unsupported major.minor version 51.0 at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(Unknown Source) at java.security.SecureClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.access$000(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at net.minecraft.server.ModLoader.addMod(ModLoader.java:172) at net.minecraft.server.ModLoader.readFromModFolder(ModLoader.java:929) at net.minecraft.server.ModLoader.init(ModLoader.java:683) at net.minecraft.server.ModLoader.Init(ModLoader.java:1357) at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:102) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:411) at net.minecraft.server.ThreadServerApplication.run(SourceFile:465) 2012-04-01 18:07:28 [sEVERE] Unexpected exception java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_IC2AdvancedMachines : Unsupported major.minor version 51.0 at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(Unknown Source) at java.security.SecureClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.access$000(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at net.minecraft.server.ModLoader.addMod(ModLoader.java:172) at net.minecraft.server.ModLoader.readFromModFolder(ModLoader.java:929) at net.minecraft.server.ModLoader.init(ModLoader.java:683) at net.minecraft.server.ModLoader.Init(ModLoader.java:1357) at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:102) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:411) at net.minecraft.server.ThreadServerApplication.run(SourceFile:465) Help?