In my twenty-two years of working with prospects and some clients, all I can say is that people are inscrutable. I don't work with clients who do not trust my advice and I spend very little time with prospects who are unresponsive. Doctors don't waste much time with patients who will not take their meds or follow his instructions. Sometimes there are good reasons for a lack of progress with a prospect, but most times they have changed their minds, will not do business with you and just don't want to tell you that. Move on.