I agree with you, about the control version. I will implement it NOW! I was thinking about it, but, at the beginning, the project was small, and after, growed a few... I don't have excuses to don't implement it now.
Aristos, well, I think that your explanations about the conditions to lose a block diagram makes sense. Because I was with some VIs opened, and appeared that message to revert. Duh, I was dumb and clicked on "no".
I have a backup copy, so, no great pain to recreate it, hopefully. But good to know that NI can help if the things really goes hard!
It was important to learn that have much ways to lose VIs....
Many thanks!
PS: Sorry for my english...