Always post without any of the DLC checked (except perhaps the race you are using). The reason they are checked is a bug in the game. You’ll be doing everyone a favor if you uncheck them before posting a challenge (did you not know you were supposed to do that?)The game won’t let you download a race you don’t have, but leaving the DLC checked makes it seem like your challenge is every race. I do believe there is a fix comming in version 1.48 that fixes this (I thought that fix was promised in the Nomad DLC, but it did not seem to work).
On another topic:
Would be awesome.
I also think an Empire/Alliance only NEC would be cool.