Right now on Men Of War, I'm on bonous mission 4 called "the airstrip". I've completed every task that's on the objectives except destroy all german planes? What's strange about that is I've looked up and down this map and every german plane that was there is now destroyed and everytime I head back to the extraction point it still won't let me end the mission?(oddly enough it even says I already completed "reach extraction"?) Why is this?