Deciphering error messages on conversion

Greetings: I am creating DAISY books from HTML files. To do this, I am utilizing the DAISY pipeline, latest download. I first save my HTML file as a DAISY DTB XML file using the HTML 1.0 to DAISY DTB script. When doing the conversion, I get an error message that says, "element bodymatter incomplete, should be in the form level level +". What does this mean? My headings do not skip levels, and all of my tags appear to be closed properly. I have attached the file, it is merely a test file that I was trying to put together to see if I could successfully create a DAISY book from HTML. While we are on this topic, are the frontmatter, bodymatter, and rearmatter styles required for successful DAISY conversion? If so, what kinds of things usually get put into frontmatter and rearmatter? Thank you, Wes Majerus