After some research, I found that Sugar Bytes is a music production company that creates virtual instruments and effects plugins, and one of their popular products is the Sugar Bytes Guitar plugin.

Remember that the keyboard is split at C3 . Notes below C3 trigger chords, while notes above C3 select and trigger the actual performance patterns.

If you are running Guitarist as a standalone app (not inside a DAW):

The most common "silent" failure in Sugar Bytes products is an invalid or missing serial number.