Don Stover appears to have logged in, selected his events and has actually sent his check for payment. When I download classmate list and put a check mark by date joined he appears with a blank date as does Mary Varga who has also paid.
I'm probably missing a simple answer but need help.

I ran your report for Don and see he has a Join Date and a Last Login date of    04/03/2013
Mary Varga, does not appear to have ever actually joined the site leading me to believe that an admin must have added her to the attendee list via the button at the bottom of the attendees page that says:    Add Classmate or Guest Attendee on your Classlist.