I try to understand the reasons of their inactivity and I never give up.
Don't forget to send to all of your affiliates at least one message a week via PSA Mailer. Send them personal emails, too. Maybe you'll not receive their response, but you'll do your work. And every work counts. Ask your sponsor what to do. He or she has his or her solutions, but why not to try on the same way to keep your own team.