XSL/XSLT one random node display, need help

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
	<xsl:output method="html" version="4.0" encoding="iso-8859-1" indent="yes"/>
	<xsl:template match="/">
		<xsl:apply-templates/>
	</xsl:template>
	<xsl:template match="channel">
		<xsl:apply-templates select="item[position()<=1]"/>
		<xsl:apply-templates select="math:random(count(item))"/>
		<xsl:copy-of select="item[position() = current()]"/>
	</xsl:template>
	<xsl:template match="image">
		<a target="_blank">
			<xsl:attribute name="href">
				<xsl:value-of select="link"/>
			</xsl:attribute>
			<img>
				<xsl:attribute name="src">
					<xsl:value-of select="url"/>
				</xsl:attribute>
				<xsl:attribute name="alt">
					<xsl:value-of select="title"/>
				</xsl:attribute>
				<xsl:attribute name="width">
					<xsl:value-of select="width"/>
				</xsl:attribute>
				<xsl:attribute name="height">
					<xsl:value-of select="height"/>
				</xsl:attribute>
			</img>
		</a>
	</xsl:template>
	<xsl:template match="item">
		<strong>
			<a target="_blank">
				<xsl:attribute name="href">
					<xsl:value-of select="link"/>
				</xsl:attribute>
				<xsl:value-of select="title" />
			</a>
		</strong>
		<xsl:apply-templates select="description"/>
	</xsl:template>
	<xsl:template match="description">
		<br>
			<xsl:value-of select="." disable-output-escaping="yes"/>
		</br>
		<br></br>
		<br></br>
	</xsl:template>
	<xsl:template match="text()"/>
</xsl:stylesheet>