strange trouble with lists

I have a docbook 5 document where adding orderedlist or itemized list
(as a child of chapter or para, so far) causes the following output:

to-fo:
     [exec] Stripping NS from DocBook 5/NG document.
     [exec] Processing stripped document.
     [exec] Making portrait pages on USletter paper (8.5inx11in)
     [exec] XPath error : Invalid context position
     [exec] xmlXPathCompiledEval: evaluation failed
     [exec] Result: 10


Then sections of the result document are missing, etc. Everything
works fine when I don't have a list. What might be the cause of
something like that?

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http://chris.chiasson.name/