Why do my line/section breaks disappear ?

Can anyone please help ?

I have been writing a series of practical police law guides called Pocketpolis. There is a free demo available on the iBook store

The problem I'm having is I write the guide using Pages. On my Pages version my line/section breaks work fine however by the time the book gets published, they disappear, leading to a messy appearance.

If anyone wants an example of what I'm talking about, you can download my book. Go to page 4. After the link for "defence" that should be the end of the page however the top of the next page appears at the bottom of page 4, when really it should start afresh on page 5. There is no line or section break, as there is on my Pages version.

Any ideas ?

Thanks

Andy