How to end Naval Academy missions ?

[storm-petrel]

I have not played for ages and have spent last half-hour searching in vain for answer to my question.

Its after doing the torpedoes exam, and sinking all the targets, message from BDU says something like "Congratulations etc. etc. you have graduated the torpedoes exam, or whatever".

I then surface and hit Escape key, which prompts 'Abandon Mission?' Y/N.

After pressing Y it prompts 'return to base'?

Press Y and am taken back to Naval Academy start screen which says, 'no exam taken'. I am starting this by selecting the Exam icon and not tutorial, so do not get what I am doing wrong.

Know its gonna be a simple one ( please ) but its driving me up the wall.

Thanks in advance to all of you nice people.....I feel silly and am off to start cooking some food now. Its cheese on toast BTW.