I don't use Kindle, and can't say how much this influences it, but your epub-file has some errors (not found by Sigil, but very much found by epubcheck 3.01)
So here goes:
- Consider renaming all the files "The Pharaoh and the Priest_00XX.htm" to something without spaces, and then regenerate the TOC
- Epubcheck doesn't like this:
<meta content="2013/10/19" name="dcterms.date of publication" />
(I usually use this form:
<meta content="2013-10-19" name="DC.date.publication" scheme="ISO8601" /> )
- and not this either:
<meta content="Public Domain" name="dcterms.right
s"" />
- remove the "
- Hope this helps