I'm new to the forums, and believe it or not, in the three years I've played SINS I had no idea there were mods.
I believe you... so Devs, if you read this, be sure to add a "Forum" button on the main menu of Rebellion...
As for your map problem, open them with notepad and check that at the begin, you have :
TXT
versionNumber 3
With today version of sins, map need to be made with forgetools III... map made with the original tools will not work...
For mod, be sure to have a mod made for your version too... as i wrote this post, there is already some mod who have updated to the last patch, diplomacy 1.34 ...