How do I import a Garage Band vocal file into an iBooks Author file

I have been successfully importing audio made in Garage Band into a book I am writing in iBooks Author. Until this morning, I would create the Garage band vocal track, save it to my desktop on my MacBook Air. Next, I import that into an iTunes playlist set up for this book Then, in iBooks Author, click on widget and choose the media widget. Then I would click on Media, and find the file in iTunes in the menu that appears in Media. I would then drag that into the widget on my iBooks Author page.

This no longer works.

Help!