You are making an ePub2 according to the version # at the top of your opf, so make sure you are following those rules. If you use Sigil or Calibre to add your cover then this should all be done automagically. But you should see something referencing 'cover' in each section (metadata, manifest, spine, and guide) of your opf. Something along the lines of:
Code:
<?xml version="1.0" encoding="utf-8"?>
<package version="2.0" unique-identifier="BookId" xmlns="http://www.idpf.org/2007/opf">
<metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
<dc:identifier opf:scheme="UUID" id="BookId">urn:uuid:6291c88b-0401-4263-8f9e-18c3aaec004a</dc:identifier>
<dc:language>en</dc:language>
<dc:title>[Title here]</dc:title>
<meta name="cover" content="cover.jpg" />
</metadata>
<manifest>
<item id="ncx" href="toc.ncx" media-type="application/x-dtbncx+xml"/>
<item id="cover.xhtml" href="Text/cover.xhtml" media-type="application/xhtml+xml"/>
<item id="cover.jpg" href="Images/cover.jpg" media-type="image/jpeg"/>
</manifest>
<spine toc="ncx">
<itemref idref="cover.xhtml"/>
</spine>
<guide>
<reference type="cover" title="Cover" href="Text/cover.xhtml"/>
</guide>
</package>
Your opf has 'cover-image' in the contents of the metadata section, and the ID in the manifest section. You need to reference the image name.... cover.jpg
Also make sure your references are pointing to the correct location. eg. If you have your images in an Images folder then the reference would be "Images/cover.jpg"
Cheers!