Hi,
As Doitsu said, you should remove all of the metadata from that html page and convert it to proper dc metadata at the book level using Sigil's metadata editor. The metadata you have is not correct for dcterms and has spaces in the name "field" which are not allowed.
So either remove it completely or change it to
Code:
name="dcterms.dateOfPublication"
or some other name without spaces.
Or better yet, convert it to be proper dc or dcterms metadata.
KevinH