I think you're casting without checking. Use instanceof >:(

2014-02-21 20:52:22 [INFO] [STDERR] java.lang.ClassCastException: codechicken.chunkloader.CommandDebugInfo cannot be cast to net.minecraft.command.CommandBase
2014-02-21 20:52:22 [INFO] [STDERR]     at StevenDimDoors.mod_pocketDim.commands.DDCommandBase.compareTo(DDCommandBase.java:87)

On a  pure fresh install server of tekkit. I am not the one having this issue, the thread is here: http://forums.technicpack.net/topic/56944-server-commands-fails/#entry466797

So ask issue questions there.