S2: Help German Manor

Hi guys... i love this game, but i have a terrible negative karma with it.
the first time i played it i went as soon as i could in the last mission and saved the game for discovering after a while that i could not finish the game anymore...
and since then every time i restart my axis campaign i get stuck after completing the first uk missions, since the only mission left after them is the german manor one and i guess something doesn't work with it: while playing it the first time i remember Koch trying to escape on a rocket, now he doesn't even appear on the map and even though i get the clues the mission requires no other location appear on the world map, leaving me no choice but to assault the last stage boss with my 6 lvl party...
any idea on how to get Koch appear??