I just took the OPF and NCX of an eBook I'm fixing up and dropped in your eBook's ID and it validates.
OPF:
Spoiler:
<package xmlns="http://www.idpf.org/2007/opf" unique-identifier="PrimaryID" version="2.0">
<metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns
pf="http://www.idpf.org/2007/opf">
<dc:title>The Silent Girl</dc:title>
<dc:language>en-US</dc:language>
<dc:identifier id="PrimaryID">urn:uuid:c22d9e01-0d3c-4009-82df-3287f82ac7eb</dc:identifier>
<dc:creator opf:file-as="Gerritsen, Tess" opf:role="aut">Tess Gerritsen</dc:creator>
<dc
ublisher>Random House Publishing Group</dc
ublisher>
<dc:date opf:event="publication">2011-07-05</dc:date>
<dc:rights>Copyright © 2011 by Tess Gerritsen</dc:rights>
<meta content="cover-image" name="cover"/>
<meta content="1.2" name="epubcheckversion"/>
<meta content="2011-06-22" name="epubcheckdate"/>
<description xmlns="http://purl.org/dc/elements/1.1/"><p></description>
</metadata>
NCX: