Don't get it.
 

I am trying to change my U-Boat in OM. Sept 1944 in Bergen, VIIC/41. Every time I change it from U-292 To another I get a CTD when I try and load the save. I am saving it while still in base and I am changing the right files ( Active user player unit and Career track ). I have done this a hundred times in TMO and have never had a problem.