That's the bad news.
The good news is that a new Margo Monroe mystery will be coming to a Kindle near you very soon! This one, tentatively titled "Ghost in the Machine", is a bit of a departure from recent Margo stories. Too long to be a short story but too short to be a whole book by itself, it's technically a novella. But don't worry, it has all the fun-filled, action-packed ghostly adventure you've comes to expect from Margo and Ernie.
In the meantime, check out this excellent article on why novellas are the future of publishing.