It appears that you are trying to link to the table of contents within the
same .html file called "introduction.html".
eBook Publisher does not like that so when links are within the same file omit the filename before the "#", like this :
Code:
<a href="#contents">Contents</a>
Aside: If that code fragment was in a .html named anything else then, you could use the line above to reference to another .html added to your eBook Publisher Spine Items window. In that case should ignore the table of contents within the code fragment's .html file and "jump" to the file named "introduction.html".
And be careful when using uppercase letters within the names used as the links since eBook Publisher is
case-sensitive and will not "link" when the names are mis-matched case-wise.
These are the
Golden Rules to achieving success with eBook Publisher.
Hopefully this will work for you!