I know that they need ticket sales to book guests, but unless they book guests from the other two shows people wont buy. I only watch Fringe, and buying coz a Lost guest is there will be pointless coz I don't even watch the show.
Even if they said, we need x amount of tickets sold to garantee this guest, it will encourage people to buy. Coz with only one guest from one show, it is alienating viewers who are fans of the other shows.
Don't take this as a rant, it's just my opinion on why people aren't booking.