small non-hotlinked citation text problem

What could cause citation text to not be hotlinked in pdf or html
output, but to be hotlinked in xhtml?

I am currently seeing it in my docbook 5 work, with xml like this
<citation>GNVNOTED<citation>

resulting in:

xhtml (works):
[<a href="#GNVNOTED" title="[GNVNOTED]"><abbr class="abbrev"><a
id="GNVNOTED_abbrev"/>GNVNOTED</abbr></a>]

html (not hotlinked):
[<a href="#GNVNOTED" title="[GNVNOTED]"><abbr class="abbrev"><a
name="GNVNOTED_abbrev"></a>GNVNOTED</abbr></a>]

fo (not hotlinked):
[GNVNOTED]

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http://chris.chiasson.name/