format-number in Saxon 8.5

Hi list,
the stylesheet below works fine with Saxon6,
00001
00022
00333
04444
55555
but not with Saxon8
001
0022
0333
04444
55555
Any idea what's wrong with it?

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="2.0"
             xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:variable name="LF" select="'&#xA;'" />
<xsl:template match="/">
       <xsl:value-of select="$LF" />
       <xsl:value-of select="format-number(1,'00000')" />
       <xsl:value-of select="$LF" />
       <xsl:value-of select="format-number(22,'00000')" />
       <xsl:value-of select="$LF" />
       <xsl:value-of select="format-number(333,'00000')" />
       <xsl:value-of select="$LF" />
       <xsl:value-of select="format-number(4444,'00000')" />
       <xsl:value-of select="$LF" />
       <xsl:value-of select="format-number(55555,'00000')" />
</xsl:template>
</xsl:stylesheet>

Manfred