Anemesis

I am going to say this would need to be done on all servers, or at least any that plan to use items within the NuclearControl mod, as it appears there is a confilt with some of the items. I have not tested this myself but am assuming this based on jfmoots comment above:

I was able to fix this issue by deleteing the mod_IC2NuclearControl-1.1.10b-mcpc-r1.zip file from the mods folder on the Server and in its place install: https://github.com/downloads/mushroomhostage/ic2-nuclear-control/mod_IC2NuclearControl-1.1.11-mcpc-r1.zip To connect to the Server you will also need to delete the IC2NuclearControl_client_v1.1.10b.zip file from the mods folder on your Local/Client computer and in its place install: http://bqt.me/mc/old/1.1.11/IC2NuclearControl_client_v1.1.11.zip