There seems to be a problem that arises in simulgear games when fortify to any connected is enabled and there are view-only borders involved. In cases where territory A has a one-way, view-only border to territory B, but they are also connected by contiguous territories that the same player controls, the engine does not allow the player to submit orders that include a fortify from A to B.  Instead it gives an error message: "Reinforcements or Fortifications not allowed for this border type".

See this game for example: http://www.wargear.net/games/view/330031

Still encountering this problem now and then on this same game.