Well I don't know. You might want to look at your stats to know that answer.
I can only guess that the people enrolled, are not actively doing anything.
If they're not actively doing anything then the question would be 'Why Not?'
And here again, I suppose only you can answer that.
Is it because you don't have a message to them entered into your ClixSense?
Is it because you don't have your email address checked so they can see it and contact you with questions?
Is it because they expected you to send them an email and/or explain more?
Is it because you purchased junk sign ups?
I mean, there is a gazillion reasons why you have 52 referrals but not making you much money.