two-level grouping

I am stuck on a two-level grouping problem. This one is slightly
different from the last one. I believe it involves nested grouping
sequences, but I have been wrong on numerous occasions before.

<book>
 <bodymatter>
   <chapter>Fun and Games</chapter>
    <a-head><img src="BK_Vocab_G09-5P2-web-images/embossed%
20arrow_opt.jpeg" alt="embossed arrow.eps"/>Definitions</a-head>

    <p>Directions: The words in this lesson may be associated with
sports and leisure activities.</p>
    <p><strong>adversary</strong> (ad<strong>B+</strong>vIr-
serB+<strong>eL</strong>) <em>n. </em>An opponent; an enemy.</p>
    <p>Tyler groaned when he saw his <strong>adversary</strong>
spinning his basketball on one finger.</p>
    <p><strong>backstretch</strong> (bak<strong>B+</
strong>stre&#774;chB+) <em>n. </em>The part  of the oval...</p>
<!--more paragraphs elements here-->
   <p>Lesson 1 b" Level I b" VOCABULARY SKILLBOOK</p>
   <pagenum page="normal" id="page_1">1</pagenum><p>PARTIAL
PRONUNCIATION KEY</p>
	<p>a&#774; pat, a&#772; pay, b0r care, E  father, e&#774; pet,
e&#772; bee,  I  about, D1&#774; pit, D1&#772; pie, br pier,
o&#774; pot,
	 o&#772; toe, b" paw, oi boy, ou out, oMo took, oMo boot, u&#774;
cut, E> urge</p>
	<image><img src="BK_Vocab_G09-5P2-web-images/BW%20oval_opt.jpeg"
alt="BW oval.eps"/></image>
   <p>LESSON 1</p>

   <a-head><img src="BK_Vocab_G09-5P2-web-images/embossed%
20arrow_opt.jpeg" alt="embossed arrow.eps"/>Completing the Sentence</
a-head>

   <p>Directions: Choose the letter of the word that best completes
the sentence.</p>
<!--more a-heads and paragraphs pagenums, etc here-->

  <chapter>Letbs Eat!</chapter>
   <a-head><img src="BK_Vocab_G09-5P2-web-images/embossed%
20arrow_opt.jpeg" alt="embossed arrow.eps"/>Definitions</a-head>
   <p>Directions: The words in this lesson may be associated with
food, eating, and cooking.</p>
   <!--more chapter and a-head sequences -->
 </bodymatter>
</book>

I am trying to add two levels
<book>
<bodymatter>
<level1>
	<chapter>Fun and Games</chapter>
		<level2>
			<a-head>Definitions</a-head>
			<p>...</p>
			<p>...</p>
			<p>...</p>
			<!--etc.-->
		</level2>

		<level2>
			<a-head>Head Text</a-head>
			<p>...</p>
			<p>...</p>
			<p>...</p>
			<!--etc.-->
		</level2>
</level1>
<level1>
	<chapter>Let's Eat</chapter>
		<level2>
			<a-head>Definitions</a-head>
			<p>...</p>
			<p>...</p>
			<p>...</p>
			<!--etc.-->
		</level2>
<!--etc-->
</level1>
</bodymatter>
</book>

<xsl:stylesheet version="2.0"
     xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml"/>

<xsl:template match="@*|node()">
	<xsl:copy>
		<xsl:apply-templates select="@*|node()"/>
	</xsl:copy>
</xsl:template>

 <xsl:template match="bodymatter">
   <xsl:copy>
       <xsl:apply-templates select="@*"/>
           <xsl:for-each-group select="*" group-starting-
with="chapter">
        <level1 class="chapter">
         <xsl:apply-templates select="current-group()"/>
        </level1>
          <xsl:for-each-group select="current-group()" group-
starting-with="a-head">
            <level2>
            <xsl:copy-of select="current-group()"/>
            </level2>
          </xsl:for-each-group>
        </xsl:for-each-group>
     </xsl:copy>
 </xsl:template>

This captures the <chapter> level1 but doesn't touch the <a-head>
level2.