I think ADSR in Envelopes supposed to do the Fade in and out.
To do with single sample, you have to click [Edit Sample] in middle right
A must have feature! Logics new sampler has it, cubase has it, and I use it all the time. Using the envelopes doesn't give you the visual that is important for a fast efficient workflow!
Logic:
Cubase:
I did this fade out with the Amplitude curve inside Sample One XT.
I hope it helps.
Alain