A question about the audio version of Path of Daggers

Does anyone know why its so hard to get a copy of the unabridged version of Robert Jordan’s The Path of Daggers on cassett? You can get every other book in the unabridged version…but not only doesn’t my library have it, I can’t find the unabridged version online at booksontape.com either (they have all the others). Even buying it is a pain in the ass. Why? What happened with this particular book that its so hard to get the tape version?

Any help solving this puzzle will be greatly appreciated.

-XT