last() and distinct-values 2.0

Hi,

I'm trying to change our stylesheets over to 2.0 and saxon 8, but am 
getting confused about the behaviour of the last() function.
My test case is below, it has a variable called $languages, with many 
<lang> elements.
I wanted to get the 3 distinct languages from there.
If I comment out the last() function, it works as I expect, but when I add 
the last() function inside the for-each loop I get it returning '2', and 
only get 1 iteration from the loop.
I expect the last() function to return 3.

Any suggestions/hints would be welcome

thanks,
Jurn

<?xml version="1.0"?>
<xsl:stylesheet version="2.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
                xmlns:fn="http://www.w3.org/2003/11/xpath-functions";>
  <xsl:template match="/">
    <xsl:variable name="languages">
      <lang>English</lang>
      <lang>English</lang>
      <lang>Chinese</lang>
      <lang>French</lang>
      <lang>French</lang>
      <lang>Chinese</lang>
      <lang>French</lang>
      <lang>Chinese</lang>
    </xsl:variable>
    <xsl:for-each select="fn:distinct-values($languages/lang)">
      <xsl:value-of select="position()"/>,
      <xsl:value-of select="."/>,
      <xsl:value-of select="last()"/>
      --
    </xsl:for-each>
  </xsl:template>
</xsl:stylesheet>