XPatch: ancestor and count

Hi,

I have some XML file, for example:
=======
<menu>
      <menuitem title="1"/>
      <menuitem title="2">
        <menuitem title="2.1"/>
      </menuitem>
      <menuitem title="3">
        <menuitem title="3.1"/>
        <menuitem title="3.2"/>
        <menuitem title="3.3"/>
        <menuitem title="3.4">
              <menuitem title="3.4.1"/>
              <menuitem title="3.4.2"/>
        </menuitem>
        <menuitem title="3.5"/>
        <menuitem title="3.6">
              <menuitem title="3.6.1"/>
              <menuitem title="3.6.2"/>
        </menuitem>
      </menuitem>
</menu>
======
and XLS transform:
======
<xsl:template match="menu">
  <table class="menu">
    <tr><td><xsl:value-of select="count(ancestor::*)"/></td><td>&#xA0;</td></tr>
    <xsl:for-each select="child::menuitem">
     <tr><td><xsl:value-of select="count(.//ancestor::*)"/></td><td>
     <xsl:value-of select="@title"/></td></tr>
    </xsl:for-each>
  </table>
</xsl:template>
======
In result the following:
======
1         - root element
2    1    - root, menu
3    2    - root, menu, menuitem "2"
5    3    - root, menu, menuitem "3", menuitem "3.4" and what???
======
http://www.w3.org/TR/1999/REC-xpath-19991116 :
* the ancestor axis contains the ancestors of the context node;
the ancestors of the context node consist of the parent of context
node and the parent's parent and so on;..

* Function: number count(node-set)
The count function returns the number of nodes in the argument node-set.
======
Why the result is 5? It should be equal 4, or not?

PS. I use Perl-5.8.5 + LibXML + LibXSLT..
--
Best regards,
Andrey V. Elsukov