I finally figured out why my message box was flashing and no messages shown
Simply because in message box options, all boxes weren't checked...
For instance, game was sending me submarines spotted, but as this box was not checked, i had nothing in the message box! lol
Now, everything is working, EXCEPT i have English voice announcing when the submarines spotted message is showing
So, in the waiting for some kind help to solve this voice issue
i'm gonna leave the box unchecked...