Tekkit ...6 more server crash

[st1jn]

Launcher/pack Version: latest development build 2.1.1

Operating System: Windows 7

Version of Java: jre6 and jre7

Description of Problem: if i start a server it will load and at the end it freezes on ...6 more

Error Messages: Check pastebin

Link to pastebin of log: http://pastebin.com/9pWwSgem

help me

[linkthegamer]

This is important part of your error:

java.lang.UnsupportedClassVersionError: net/minecraft/server/mod_IC2AdvancedMachines : Unsupported major.minor version 51.0

List the architecture of your PC and Java (that is 32-bit or 64-bit) just because that is usually important, Google to find out how to learn those. also the ...6 more just means there are 6 more lines that have been suppressed because they are not important if I remember right.