I changed the top of your stylesheet to use saxon 6's node-set extension
rather then MS's.

I get the result below, no empty summary element, so perhaps there is a
bug in the processor you are using.

David

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:fx="http://icl.com/saxon">
<xsl:output indent="yes"/>



$ saxon sum.xml sum.xsl
<?xml version="1.0" encoding="utf-8"?>
<result xmlns:fx="http://icl.com/saxon">
   <foo>
      <B code="FOO">red</B>
      <B code="FOO">blue</B>
      <B code="FOO">blue</B>
      <B code="FOO">green</B>
   </foo>
   <bar>
      <B code="BAR">green</B>
      <B code="BAR">red</B>
      <B code="BAR">green</B>
      <B code="BAR">green</B>
      <B code="BAR">blue</B>
   </bar>
   <foobar_summary>
      <summary_for_foo>
         <summary code="FOO" color="red">1</summary>
         <summary code="FOO" color="blue">2</summary>
         <summary code="FOO" color="green">1</summary>
      </summary_for_foo>
      <summary_for_bar>
         <summary code="BAR" color="green">3</summary>
         <summary code="BAR" color="red">1</summary>
         <summary code="BAR" color="blue">1</summary>
      </summary_for_bar>
   </foobar_summary>
   <foo>
      <B code="FOO">green</B>
      <B code="FOO">blue</B>
      <B code="FOO">red</B>
      <B code="FOO">green</B>
      <B code="FOO">green</B>
      <B code="FOO">green</B>
      <B code="FOO">green</B>
   </foo>
   <bar>
      <B code="BAR">green</B>
      <B code="BAR">green</B>
      <B code="BAR">green</B>
      <B code="BAR">blue</B>
      <B code="BAR">blue</B>
   </bar>
   <foobar_summary>
      <summary_for_foo>
         <summary code="FOO" color="green">5</summary>
         <summary code="FOO" color="blue">1</summary>
         <summary code="FOO" color="red">1</summary>
      </summary_for_foo>
      <summary_for_bar>
         <summary code="BAR" color="green">3</summary>
         <summary code="BAR" color="blue">2</summary>
      </summary_for_bar>
   </foobar_summary>
</result>


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