Tekkit Classic Issues with Tekkit Server 3.0.4

I recently tried starting a Tekkit Server, I watched tutorials and guides and such and have hosted many servers in the past. I get this strange error when trying to launch the tekkit server, something about nether ores? I'll post it:


C:\Users\Sean\Desktop\Tekkit Server>java -Xmx3G -Xms2G -jar Tekkit.jar nogui
182 recipes
27 achievements
17:15:21 [INFO] Starting minecraft server version 1.2.5
17:15:21 [INFO] Forge Mod Loader version @MAJOR@.@MINOR@.@REV@.@BUILD@ for Minec
raft @MCVERSION@ loading
17:15:21 [INFO] Loading mods from C:\Users\Sean\Desktop\Tekkit Server\mods
17:15:21 [SEVERE] java.lang.UnsupportedClassVersionError: net/minecraft/server/m
od_NetherOres : Unsupported major.minor version 51.0
17:15:21 [SEVERE] at java.lang.ClassLoader.defineClass1(Native Method)
17:15:21 [SEVERE] at java.lang.ClassLoader.defineClassCond(Unknown Source)

17:15:21 [SEVERE] at java.lang.ClassLoader.defineClass(Unknown Source)
17:15:21 [SEVERE] at java.security.SecureClassLoader.defineClass(Unknown S
ource)
17:15:21 [SEVERE] at java.net.URLClassLoader.defineClass(Unknown Source)
17:15:21 [SEVERE] at java.net.URLClassLoader.access$000(Unknown Source)
17:15:21 [SEVERE] at java.net.URLClassLoader$1.run(Unknown Source)
17:15:21 [SEVERE] at java.security.AccessController.doPrivileged(Native Me
thod)
17:15:21 [SEVERE] at java.net.URLClassLoader.findClass(Unknown Source)
17:15:21 [SEVERE] at java.lang.ClassLoader.loadClass(Unknown Source)
17:15:21 [SEVERE] at sun.misc.Launcher$AppClassLoader.loadClass(Unknown So
urce)
17:15:21 [SEVERE] at java.lang.ClassLoader.loadClass(Unknown Source)
17:15:21 [SEVERE] at java.lang.ClassLoader.loadClass(Unknown Source)
17:15:21 [SEVERE] at java.lang.Class.forName0(Native Method)
17:15:21 [SEVERE] at java.lang.Class.forName(Unknown Source)
17:15:21 [SEVERE] at cpw.mods.fml.common.Loader.loadModClass(Loader.java:4
40)
17:15:21 [SEVERE] at cpw.mods.fml.common.Loader.attemptFileLoad(Loader.jav
a:497)
17:15:21 [SEVERE] at cpw.mods.fml.common.Loader.load(Loader.java:375)
17:15:21 [SEVERE] at cpw.mods.fml.common.Loader.loadMods(Loader.java:527)
17:15:21 [SEVERE] at cpw.mods.fml.server.FMLBukkitHandler.onPreLoad(FMLBuk
kitHandler.java:113)
17:15:21 [SEVERE] at net.minecraft.server.MinecraftServer.init(MinecraftSe
rver.java:118)
17:15:21 [SEVERE] at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:426)
17:15:21 [SEVERE] at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:492)
17:15:21 [SEVERE] Unexpected exception
java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_NetherOres : Un
supported 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:440)
at cpw.mods.fml.common.Loader.attemptFileLoad(Loader.java:497)
at cpw.mods.fml.common.Loader.load(Loader.java:375)
at cpw.mods.fml.common.Loader.loadMods(Loader.java:527)
at cpw.mods.fml.server.FMLBukkitHandler.onPreLoad(FMLBukkitHandler.java:
113)
at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:118)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:426)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
>

Well, there you go. If you have any idea whats wrong and if I can fix it, please let me know.

Remove all versions of Java you may have and get Java 7, download link can be found at technicpack.net.

Thanks, I'll try that now.

Is changing enviromental variables a required thing?

Ok I think I see where the problem was. I had 6 different versions of Java on my computer (I used to do a lot of Java stuff back in the day LOL) so I deleted them all, and installed the newest version of Java 7 x64. I looked at my enviromental variables, and the "PATH" one was set to a very old version of Java. I fixed the enviromental variables and now it worked. Let this be a lesson to all you others having issues out there. I'll lock this thread.