xsl:template rules seems to be ignored

I am quite new to XSL and I am trying to write a stylesheet to process a
log file generated with Apache Logging framework.

The XML file is like this

=== begin log.xml ===
<?xml version="1.0" ?>
<!DOCTYPE log4j:eventSet SYSTEM "log4j.dtd" [
        <!ENTITY data SYSTEM "server.xml">
        ]
>

<log4j:eventSet version="1.2"
xmlns:log4j="http://jakarta.apache.org/log4j/">
        &data;
</log4j:eventSet
=== end log.xml ===

and my stylesheet is like this

=== begin log.xsl ===
<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
<xsl:stylesheet version="1.0"
        xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
        xmlns:log4j="http://jakarta.apache.org/log4j">

<xsl:output method="html" />

<xsl:template match="log4j:eventSet">
	<!-- Do something here -->
</xsl:template>
</xsl:stylesheet>
=== end log.xsl ===

But my template rules are ignored.
Why?

Regards

-- 
Stefano Lampis