Soundboard is looking for a simple note on/note off signal from a MIDI device to trigger the sounds; much like a pressing a key or hitting a pad. If you are unsure how to configure your device for this behavior, please consult your device's documentation. You can also usethe free utility, MIDI Monitor, to help troubleshoot.
Using sliders or knobs to adjust volume or panning is currently not available in Soundboard. We do plan on adding this functionality in a future update.