First, they had to actually read the first chapter. Getting teenagers to read is like getting Presbyterians to sing songs written in the past hundred years. It happens but is rare.
Second, they had to show up. After all we meet at 6:45 am. AM...the juxtapostion of those two letters is the beginning of many nightmarish scenarios for the average teen.
Third, they needed to like it or the first two might not happen again. The only thing most of my youth are used to reading by choice is gaming magazines, menus and their wall on facebook. I do have some who read but they are no where near the majority.