Sadly, it's already set up like that.
Here is the opf file I get from Indesign. Do you think it's the space in the chapter name causing the trouble? Although, I get the same error for chapters that just have one word in the title and no spaces.
Code:
<?xml version="1.0"?> <package xmlns="http://www.idpf.org/2007/opf"
xmlns:dc="http://purl.org/dc/elements/1.1/" unique-identifier="bookid"
version="2.0"><metadata><meta name="generator" content="Adobe
InDesign"/><dc:title/><dc:creator/><dc:subject/><dc:description/><dc:publisher>LittleRed</dc:publisher><dc:date>2011-06-24<dc:date>2011-06-20</dc:date><dc:source/><dc:relation/><dc:
coverage/><dc:rights/><dc:identifier
id="bookid">ISBNnumber</dc:identifier><dc:language>en</dc:language></metadata><manifest><item id="ncx"
href="toc.ncx" media-type="application/x-dtbncx+xml"/><item id="cover"
href="Cover.xhtml" media-type="application/xhtml+xml"/><item
id="title-page" href="Title%20Page.xhtml"
media-type="application/xhtml+xml"/><item id="dedication"
href="Dedication.xhtml" media-type="application/xhtml+xml"/><item
id="acknowledgements" href="Acknowledgements.xhtml"
media-type="application/xhtml+xml"/><item id="article"
href="Article.xhtml" media-type="application/xhtml+xml"/><item
id="prologue" href="Prologue.xhtml"
media-type="application/xhtml+xml"/><item id="chapter-one"
href="Chapter%20One.xhtml" media-type="application/xhtml+xml"/><item
id="chapter-two" href="Chapter%20Two.xhtml"
media-type="application/xhtml+xml"/><item id="chapter-three"
href="Chapter%20Three.xhtml" media-type="application/xhtml+xml"/><item
id="chapter-four" href="Chapter%20Four.xhtml"
media-type="application/xhtml+xml"/><item id="chapter-five"
href="Chapter%20Five.xhtml" media-type="application/xhtml+xml"/><item
id="chapter-six" href="Chapter%20Six.xhtml"
media-type="application/xhtml+xml"/><item id="chapter-seven"
href="Chapter%20Seven.xhtml" media-type="application/xhtml+xml"/><item
id="chapter-eight" href="Chapter%20Eight.xhtml"
media-type="application/xhtml+xml"/><item id="chapter-nine"
href="Chapter%20Nine.xhtml" media-type="application/xhtml+xml"/><item
id="chapter-ten" href="Chapter%20Ten.xhtml"
media-type="application/xhtml+xml"/><item id="chapter-eleven"
href="Chapter%20Eleven.xhtml" media-type="application/xhtml+xml"/><item
id="copyright" href="Copyright.xhtml"
media-type="application/xhtml+xml"/><item id="authors-note"
href="Authors%20Note.xhtml" media-type="application/xhtml+xml"/><item
id="promo" href="Promo.xhtml" media-type="application/xhtml+xml"/><item
id="x9cov-fmt-jpeg" href="images/cov_fmt.jpeg"
media-type="image/jpeg"/><item id="x-gg-cov-fmt-jpeg"
href="images/6_GG_COV_fmt.jpeg"
media-type="image/jpeg"/><item id="a90-cov-fmt-jpeg"
href="images/a97_COV_fmt.jpeg" media-type="image/jpeg"/><item
id="littlered-address-line-fmt-jpeg"
href="images/littlered_address_line_fmt.jpeg"
media-type="image/jpeg"/><item id="littlered-full-logo-blac-fmt-jpeg"
href="images/littlered_Full_Logo_Blac_fmt.jpeg"
media-type="image/jpeg"/><item id="littlered-title-page-fmt-jpeg"
href="images/littlered_Title_Page_fmt.jpeg" media-type="image/jpeg"/><item
id="grant-logo-line-bigger-fmt-jpeg"
href="images/Grant_logo_line_bigger_fmt.jpeg"
media-type="image/jpeg"/><item id="css" href="template.css"
media-type="text/css"/></manifest>
<spine toc="ncx"><itemref
idref="cover"/><itemref idref="title-page"/><itemref
idref="dedication"/><itemref idref="acknowledgements"/><itemref
idref="article"/><itemref idref="prologue"/><itemref
idref="chapter-one"/><itemref idref="chapter-two"/><itemref
idref="chapter-three"/><itemref idref="chapter-four"/><itemref
idref="chapter-five"/><itemref idref="chapter-six"/><itemref
idref="chapter-seven"/><itemref idref="chapter-eight"/><itemref
idref="chapter-nine"/><itemref idref="chapter-ten"/><itemref
idref="chapter-eleven"/><itemref idref="copyright"/><itemref
idref="authors-note"/><itemref idref="promo"/></spine></package>