I'm designing a book with each chapter in a separate file. The file is setup as reader spreads beginning with a single odd number page and ending with a single even number page. I then combine the files using Indesign's book feature and export the "book" as a pdf. What I expect to see in the pdf is the last page of the chapter 1 file be beside the first page of the chapter 2 file as a spread. Instead, the two pages appear as two single pages. Am I doing something wrong?