Well guys... apparently I'm dumb as hell...
I just had my Steam Account hacked by a Russian hacker (I know its location from the emails that came to me)...
so I won't be able to develop my Mod until Steam Support recovers my account, because obviously I cannot run the game.
I don't even want to say how I got my account hacked... because that's really a stupid way.
I'll let you know as soon as I get my account back... but I honestly don't know how long it will take, it's the first time I've been fooled so easily.