It's possible:
* You're remembering the title incorrectly. Could you double-check the title or provide any other information about the novella (author, genre, etc.)?
* The novella was never published. It might be a work in progress or an unpublished piece.
* The novella is part of a larger collection. The ISBN you're looking for might be for the entire collection, not the individual novella.
Please provide more context or information to help me locate the correct ISBN.