[Problem by the tekkit classic server]

i got this problem by my tekkit classic server PLEASE HELP

16:51:26 [INFO] Starting minecraft server version 1.2.5
16:51:26 [INFO] Attempting early MinecraftForge initialization
16:51:26 [INFO] Completed early MinecraftForge initialization
16:51:26 [INFO] Forge Mod Loader version 2.2.91.173 for Minecraft 1.2.5 loading
16:51:26 [INFO] Loading mods from C:\Users\AntonFagerberg\Desktop\server tekkit\mods
16:51:26 [WARNING] Failed to load mod class net/minecraft/server/mod_NetherOres.class in C:\Users\AntonFagerberg\Desktop\server tekkit\mods\mod_NetherOres.jar
16:51:26 [SEVERE] Zip file mod_NetherOres.jar failed to read properly
16:51:26 [INFO] File mod_NetherOres.jar contained no mods
16:51:26 [INFO] Directory weaponmod contained no mods
16:51:26 [SEVERE] A problem has occured during mod loading. Likely a corrupt jar is located in your mods directory
16:51:26 [SEVERE] cpw.mods.fml.common.LoaderException: cpw.mods.fml.common.LoaderException: java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_NetherOres : Unsupported major.minor version 51.0
16:51:26 [SEVERE]       at cpw.mods.fml.common.Loader.load(Loader.java:436)
16:51:26 [SEVERE]       at cpw.mods.fml.common.Loader.loadMods(Loader.java:606)
16:51:26 [SEVERE]       at cpw.mods.fml.server.FMLBukkitHandler.onPreLoad(FMLBukkitHandler.java:134)
16:51:26 [SEVERE]       at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:135)
16:51:26 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:438)
16:51:26 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
16:51:26 [SEVERE] Caused by: cpw.mods.fml.common.LoaderException: java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_NetherOres : Unsupported major.minor version 51.0
16:51:26 [SEVERE]       at cpw.mods.fml.common.Loader.loadModClass(Loader.java:527)
16:51:26 [SEVERE]       at cpw.mods.fml.common.Loader.attemptFileLoad(Loader.java:562)
16:51:26 [SEVERE]       at cpw.mods.fml.common.Loader.load(Loader.java:419)
16:51:26 [SEVERE]       ... 5 more
16:51:26 [SEVERE] Caused by: java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_NetherOres : Unsupported major.minor version 51.0
16:51:26 [SEVERE]       at java.lang.ClassLoader.defineClass1(Native Method)
16:51:26 [SEVERE]       at java.lang.ClassLoader.defineClassCond(Unknown Source)
16:51:26 [SEVERE]       at java.lang.ClassLoader.defineClass(Unknown Source)
16:51:26 [SEVERE]       at java.security.SecureClassLoader.defineClass(Unknown Source)
16:51:26 [SEVERE]       at java.net.URLClassLoader.defineClass(Unknown Source)
16:51:26 [SEVERE]       at java.net.URLClassLoader.access$000(Unknown Source)
16:51:26 [SEVERE]       at java.net.URLClassLoader$1.run(Unknown Source)
16:51:26 [SEVERE]       at java.security.AccessController.doPrivileged(Native Method)
16:51:26 [SEVERE]       at java.net.URLClassLoader.findClass(Unknown Source)
16:51:26 [SEVERE]       at java.lang.ClassLoader.loadClass(Unknown Source)
16:51:26 [SEVERE]       at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
16:51:26 [SEVERE]       at java.lang.ClassLoader.loadClass(Unknown Source)
16:51:26 [SEVERE]       at java.lang.ClassLoader.loadClass(Unknown Source)
16:51:26 [SEVERE]       at java.lang.Class.forName0(Native Method)
16:51:26 [SEVERE]       at java.lang.Class.forName(Unknown Source)
16:51:26 [SEVERE]       at cpw.mods.fml.common.Loader.loadModClass(Loader.java:494)
16:51:26 [SEVERE]       ... 7 more
16:51:26 [SEVERE] Unexpected exception
cpw.mods.fml.common.LoaderException: cpw.mods.fml.common.LoaderException: java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_NetherOres : Unsupported major.minor version 51.0
        at cpw.mods.fml.common.Loader.load(Loader.java:436)
        at cpw.mods.fml.common.Loader.loadMods(Loader.java:606)
        at cpw.mods.fml.server.FMLBukkitHandler.onPreLoad(FMLBukkitHandler.java:134)
        at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:135)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:438)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: cpw.mods.fml.common.LoaderException: java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_NetherOres : Unsupported major.minor version 51.0
        at cpw.mods.fml.common.Loader.loadModClass(Loader.java:527)
        at cpw.mods.fml.common.Loader.attemptFileLoad(Loader.java:562)
        at cpw.mods.fml.common.Loader.load(Loader.java:419)
        ... 5 more
Caused by: java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_NetherOres : Unsupported major.minor version 51.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(Unknown Source)
        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 java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Unknown Source)
        at cpw.mods.fml.common.Loader.loadModClass(Loader.java:494)
        ... 7 more