[Zander]

then you should have gotten a message saying mission accomplished.
Try this, play the mission "African Bees nest?", and see if you get the "mission accomplished" message after you leave the waters of Gambia.
If you don't hear that message, then that is why you don't know that the mission is accomplished.



"I got the samples then it tells me to head to a liberty port in Taihiti."

This part I don't remember. There's also the freighter and the submarine that you have to deal with.