The problem with 9781475233636 appears to be that Goodreads does not have the ISBN you provided associated with that title in their database. Therefore, the API returns an error code to the GoodReviews plugin when it searches for a record for that ISBN.
To illustrate, if you go to Goodreads.com and search for 9781475233636, you receive an error page:
If you search for the book by title ("blood rites") many results are returned, including the record for your title. However, the Goodreads record for your title ( http://www.goodreads.com/book/show/13070346-blood-rites ) doesn't display an ISBN associated with it, which means that the Goodreads API can't retrieve your title by using the ISBN.
The current version of the GoodReviews plugin only allows searching Goodreads by using the ISBN. I plan to add a feature that enables searching by Goodreads ID in addition to ISBN, but I do not yet have a timeline for that addition to the plugin.
In the meantime, the best course of action would be to contact a Goodreads librarian and request that they add the appropriate ISBN to their record for your title. When the ISBN issue is corrected, GoodReviews should be able to retrieve the title without a problem.
I hope that helps. Please let me know if I can be of further assistance.