The program simply checks and counts all users who signed up the day before dailymail ran with a MySQL statement:
// count new users
$cmd = "select id from $utable where list = '$list' and cnf = '1' and dateadd = '" . date("Y-m-d",mktime(0,0,0,date("m"),date("d")-1,date("Y"))) . "'";
Are you sure you had signups the day before?
Regards