Psychtoolbox: how to play sound according to keypress?

Hello!

I need to program an experiment where keypresses should play music. For example, I have 4 buttons and each of them has to start a sound file once it is pushed, and those buttons have to be pushed variously to produce various combination of sounds. I found BasicSoundScheduleDemo in Psychtoolbox, but I haven't been able to make it work for myself in my code.

I do not get any particular errors or the same errors all the time. My biggest problem is that despite seemingly correct code (very similar to the aforementioned demo) sound does not play.

I am not going to put all my code here right away as it is a bit long. Maybe you have any idea why the sound may not be produced in Psychtoolbox (and when I run BasicSoundScheduleDemo, everything works).

If not, then I can post more info in the comments.