DOCBOOK-APPS: no ? in the prolog?

Well, I've taken care of some of the errors that have been generated 
from improper markup syntax.  But there are some that I'm unsure.  So I 
post this simple question -- are question marks (?) not allowed in the 
prolog?  The first error message I get is this one:

openjade:./InfoServices_doc.xml:1:0:E: character "?not allowed in prolog

which really seems strange to me.  The only question mark in my entire 
document is the one in the XML declaration, which I thought was 
required.  The document starts off like this:

<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
	"docbookx/4.1.2/docbookx.dtd"
	[
		<!ENTITY % entitiesfile SYSTEM "entities.txt">
		%entitiesfile;
	]>
<book>
	<part>
		<title>Overview</title>
		<chapter>
			<title>About this Documentation</title>


I've also tried it with putting a space before the closing "?>" tag, and 
that seems not to make a difference.

any clues?



Erik