There is a scam going around DA. Hopefully this isn't happening to you, because you are a very talented artist, but it has happened to someone I know.
Basically what these people do is watch you and fave you. Then they'll start demanding you fave work they like, give points, premium subscriptions and more to themselves and others. If you don't, they flame, and disrespect you constantly. The person I know who had this happen to her had to leave DA entirely for six weeks. She complained to the mods, but unfortunately, these people have quite a number of accounts. If one gets banned or blocked, they use another, then another, ad inf.
Reason #2: If your work was faved by someone who is very popular, then it would have gotten a lot more exposure. This also goes for your work appearing in a popular club with lots of members in it. The more people who see your work, the more likely you are to get followers. I submit my work to quite a number of clubs every day, and my watcher count recently topped 650.
I'm really hoping it's the second reason. Your work deserves all the exposure it can get.