Well after the 2nd mission my brother told me about the war stuff and i had to start the "south-asia" mission.
I didn't finish it and left the game.
Now, when I go into Career there are several missions I already played (including the trainings).
So to go on with the campaign I chose "Heliport".
My brother told me the story again and I said "No thanks". Next there is the scene where I shall accept the "whaling" mission. So I choose that.
-> After that, I get back to the carreer menu. Currently I see no possibility to go on with the campaign ;( I guess "revert" will put the campaign to start?