Can't assign sonar conatct to Torpedo

[Spuky05]

Hey Guys,
I just bought Dangerous Waters because of the steam sale, looked up some nice tutorials and im on my first Mission yet. I did the TMA stuff and so on and im now Ready to fire, however I select Sierra 2 at the fire Station and click on my Torpedo tube but it doesnt work if I do snapshots or visual contacts it works but not the Sierra ones, what am i doing wrong?
Greetings Spuky05