milch cow - change of sub?

[UAbel]

i tried yesterday for my first time to dock at a milch cow marked on the map in the middle of the ocean. everything was ok: full load of fuel and torpedos after one day but... when i reload the game i had a message "antenna and periscoped destroyed". Switching to external view it seems that my sub were now the milch cow, which is actually without turret. in no way i succeded to solve this problem.
can anybody help me to correct it?
i play with NYGM 2.5 and sh3commander (full patched and correctly installed) and till now was everything ok.