We are having troubles getting Google to index the PDF files in our site. There are about 50 PDF and range in size for 20 KB to a little under two megs. They are not protected, can be read anonymously, and inside of PDF Reader, you can search the document.

They are listed in the SiteMap.xml. I can even look at the IIS logs and see Googlebot reading the PDF files, but, except for five, they are never included in the search results.

If I do a filetye:pdf, only five PDFs showed up. If I search for text I know is inside a PDF, the PDFs never show up (except for the five that are indexed).

Does anyone have any idea why the over 45+ PDF document are not being included in the index, even though they are in the sitemap and Googlebot is reading them?