It was also mentioned that he didn't know about it since he died before the book was published.
The TV Series, the 2 live action movies and the animated sequel to the 1961 original have no connection to the book's sequel.
Not to say the animated one is bad, I felt that if they looked at it they would have thought that the story wasn't strong enough to satisfy a 70 minute movie even if it's a straight to Video/DVD.