Help With Upgrading Server

[Rocky-Rakun]

Not sure if this is the correct forum, if it isn't I'm sorry x.x

Well I recently upgraded to the latest Tekkit and when I tried to log in I got this error

2013-02-24 13:24:17 [sEVERE] Encountered an unexpected exception NoClassDefFoundError

java.lang.NoClassDefFoundError: l

at a.<init>(CrashReport.java:27)

at a.a(CrashReport.java:319)

at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:673)

at ho.r(DedicatedServer.java:269)

at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:599)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)

at fy.run(SourceFile:849)

Did I do something wrong?

[Rocky-Rakun]

Also when I try to log it says

"Server Closed"