First of all, hello

I've been lurking this forum for some time, but this particular trouble (?) made me to post
I run TMO2.5 + RSRDCv502 + RSRDC Patch + OTC 1.5 for RSRDCv502.
After I installed OTC I noticed some strange thing and I can't find anything that could say is it normal or not.
The problem is: when I start a new mission, or load savegame, when I order to dive (D key) or suface (S key), I hear the "dive/surface" audio tracks only for the first time I dive/surfase after mission been started (loaded). All the other times I dive/surface I hear only standard "yes sir, dive" of "surface the ship" audio, until I save-exit game-load. Before OTC audios such "Dive planes set for normal dive!... Blow main ballast! *BULB* *BULB* *BULB*" played everytime I hit D key. Is it normal or not?
Regarding everything else game works absolutely fine and all mod are great indeed.
Sorry for my english, and thanks to all who will help.