Hey!

Me and my friends recently started playing Sins again with the Star Trek Armada 3 mod. We played for a few hours and eventually saved the progress to come back to it later. When we tried to load the game again, my friends got a error message saying they are not running the same version. 

Though once we start a new game it works perfectly fine, and when we saved that one and tried to reload the save file without leaving the game, we had the same problem. Are we doing something wrong?

I have the forgotten worlds DLC and they don't but why can they join a game and play without problem, but not be able to rejoin a previous save file?