Okay, I'm going to ask a stupid question AGAIN. Still in my game against dakkerm (#417086), a Russian naval brigade landed in Oulu (hex 180.85) and took control of the city and port. It is July 1941, the Baltic Sea is not frozen in ice. So why is my valiant unit not being supplied by sea? A level 2 port should provide 40 supply, no ? More enough than the 10 needed for my naval brigade.

Did I miss something ? A specific rule?
Thank you for your answer.