iTunes PDFs not seen as "Books"/not recognized when exporting

[macstatic]

I have an iTunes library which contains many PDFs, but for some reason they don't show up in the "Books" library section, but rather in "Music".

The rather cumbersome workaround to this is to drag the PDF files over to the Finder desktop, delete them in iTunes (taking notes of which playlists they belong to etc.) then drag them into iTunes again. This time they magically pop up in the "Books" library section.
I'm hoping there's a simpler way to make PDF files go into the correct library section -is there?

(the reason this is a problem is because I've tried to move (export) my iTunes library to another hard drive, only to find out that all my PDF files were missing! However, I tried to insert (drag from the Finder into iTunes) a PDF file or two (for testing purposes) before exporting, and they all came through fine).

 

[macstatic]

A little update...
I got the (obvious really) idea that I could also try to make a "PDF documents" playlist and export it as XML (highlight the playlist I want to export, then choose: File-Library-Export playlist) in addition to exporting my complete library, but for some reason the resulting document has no entries in it! No wonder the library export won't include them either then.

The XML file looks OK, with its structure and all, but like I said there are no actual file entries there. Obviously my library and/or iTunes has issues recognizing the PDF files I have in it (still, I have no problems viewing them from within iTunes, it's just that exporting them doesn't work). What gives?

I'm on iTunes 9.2.1

 

[Night Spring]

Upgrading to 10.1 might improve pdf handling. Also, try doing a "Get Info" on a pdf that is showing up in Music, and click option tab, and check what its Media Kind is. If setting the Media Kind to "book" solves your problem, you can then select all misbehaving pdf files and change their Media Kind to "book" at once.

 

[macstatic]

Being on a Powerbook G4 with MacOS 10.4.11 this seems to be the latest version I can use. But I'm considering upgrading to 10.5.x (Leopard), though I don't know if that entitles me to iTunes 10 or if that's Intel only.

Your suggestion partly helped.
I was able to change their media kind all to "Book", but upon exporting I'm still left with just the following file. As you can see there are no entries although the playlist contained 57 PDF files set to "Book".

Then I put a music file in that same playlist, did a new export and took a look at the XML file using TextEdit. Much to my amazement the music file is shown in the XML listing, but nothing else. This leads me to believe that there is some kind of limitation in iTunes (or my version).
Can someone here try to create a playlist with some PDF files in their iTunes collection, then export (File-Library-Export playlist), taking care to choose "XML" as the format, and finally open it in a text editor such as TextEdit and tell me if the PDF files are shown there?