Submitting art to a group doesn't necessarily mean that you'll instantly get comments ... groups do help spread peoples art to others but it does not necessarily mean that they'll comment and fav (unfortunately) and because this group is still quite small there is a lesser chance of people commenting and faving work.
Don't worry I know how you feel, sometimes when I submit artwork I expect a higher yield then what I want, however I use this experience to try and improve my art and reach for new limits