I am pretty new to XSL. I'm trying to import the contents of a
well-formed XML document into an XSL file during processing. Everything
I've read on this says that the following should work:

<xsl:copy-of select="document('header.xml')"/>

But nothing happens. The Row elements in header.xml never get imported.
I don't get any processing errors. I've also tried in the select
attribute appending "/node()" and "/Header/node()" and a few other
things.

Here's the contents of header.xml:

<?xml version="1.0" encoding="UTF-8"?>
<Header xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"
xmlns:x="urn:schemas-microsoft-com:office:excel">
					<Row>
						<Cell ss:StyleID="s85"><Data ss:Type="String">Changes are not
pushed back to InfoPath! </Data></Cell>
						<Cell ss:StyleID="s84"/>
						<Cell ss:StyleID="s84"/>
					</Row>
					<Row ss:AutoFitHeight="0" ss:Height="35.25">
						<Cell ss:StyleID="s48"><ss:Data ss:Type="String"
						xmlns="http://www.w3.org/TR/REC-html40"><B>CMS</B><Font> ::
Hardware Quote</Font></ss:Data></Cell>
					</Row>
</Header>