Sezonk

Hello Guys, i have a little Problem with my Tekkit Server, when I start the server, the error is 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.defineClass(ClassLoader.java:634) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:277) at java.net.URLClassLoader.access$000(URLClassLoader.java:73) at java.net.URLClassLoader$1.run(URLClassLoader.java:212) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at java.lang.ClassLoader.loadClass(ClassLoader.java:321) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) at java.lang.ClassLoader.loadClass(ClassLoader.java:314) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:264) at cpw.mods.fml.common.Loader.loadModClass(Loader.java:494) ... 7 more System: Intel® Core™ i7-2600K Quad-Core Ram 32GB java version "1.6.0_18" OpenJDK Runtime Environment (IcedTea6 1.8.13) (6b18-1.8.13-0+squeeze2) OpenJDK 64-Bit Server VM (build 14.0-b16, mixed mode) I think is a java Problem, anyone can help me pls ?. greetz