xsl:value-of not allowed inside a stylesheet

Hi!

I getting this sort of error message from XALAN StylesheetHandler:
XSLT error: (StylesheetHandler) xsl:value-of not allowed inside a stylesheet.
(file:///var/www/xslt/Header.xsl, line 62, column 85)

The situation is the same if I use xsl:copy-of.

The part of the Header.xsl what seems to be wrong looks like this:
<p><b>Message count= </b><xsl:value-of select="$NumberOfMessages" /></p>

Since the value comes from a variable, the list of variables is 
in a separate file. The variable is like this:

        <xsl:variable name="NumberOfMessages">
		<xsl:for-each select="Document">
		<xsl:value-of select="count(Information)" />
		</xsl:for-each>
	</xsl:variable>

The xml file syntax is like this:
<?xml version="1.0"  encoding="ISO-8859-1" standalone="yes"?>
<Document>
<Information SignStatus="Open">
    <Time>01/09/09</Time>
    <Clock>01:45:03</Clock>
    <Sender>Moilanen Jarkko</Sender>
    <Subject id="0000000004" id2="001">3. JPr hyökkäyskäsky Haminassa</Subject>
    <Subject2>Xsl- muutokset</Subject2>
    <Infofield>
    <Topic>Include hommat ei pelaa</Topic>
    </Infofield>
</Information>
<Information SignStatus="Signed">
    <Time>01/09/10</Time>
    <Clock>11:45:03</Clock>
    <Sender>Moilanen Jarkko</Sender>
    <Subject id="0000000004" id2="002">RE:3. JPr hyökkäyskäsky Haminassa</Subject>
    <Subject2>Xsl- muutokset</Subject2>
    <Infofield>
    <Topic>Include hommat ei pelaa</Topic>
    </Infofield>
</Information>


Could some one tell me the reason to this error message and solution to this
situation/ prob. 

Cheers
Jarkko

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