I'm facing a problem. I can't get the thumbnail image of the child page to display.

Can anyone help?

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xsl:stylesheet [ <!ENTITY nbsp "&#x00A0;"> ]>
<xsl:stylesheet 
  version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
  xmlns:msxml="urn:schemas-microsoft-com:xslt" 
  xmlns:umbraco.library="urn:umbraco.library" xmlns:Exslt.ExsltCommon="urn:Exslt.ExsltCommon" xmlns:Exslt.ExsltDatesAndTimes="urn:Exslt.ExsltDatesAndTimes" xmlns:Exslt.ExsltMath="urn:Exslt.ExsltMath" xmlns:Exslt.ExsltRegularExpressions="urn:Exslt.ExsltRegularExpressions" xmlns:Exslt.ExsltStrings="urn:Exslt.ExsltStrings" xmlns:Exslt.ExsltSets="urn:Exslt.ExsltSets" 
  exclude-result-prefixes="msxml
 umbraco.library Exslt.ExsltCommon Exslt.ExsltDatesAndTimes 
Exslt.ExsltMath Exslt.ExsltRegularExpressions Exslt.ExsltStrings 
Exslt.ExsltSets ">

<xsl:output method="xml" omit-xml-declaration="yes"/>

<xsl:param name="currentPage"/>

<xsl:template match="/">

<!-- The fun starts here -->

  <div id="staff_list_container">
    <ul>
      <xsl:for-each select="$currentPage/* [@isDoc and string(umbracoNaviHide) != '1']">
      <li>
        <div class="info">
          <h1>
            <a href="{umbraco.library:NiceUrl(@id)}">
              <xsl:value-of select="@nodeName"/>
            </a>
          </h1>
          <xsl:if test="jobTitle != ''">
            <p><xsl:value-of select="jobTitle" /></p>
          </xsl:if> 
          <div class="details">
            <xsl:if test="staffPhoneNumber != ''">
              <p><xsl:value-of select="staffPhoneNumber" /></p>
            </xsl:if>
            <xsl:if test="staffEmailAddress != ''">
              <p>
                <a>
                  <xsl:attribute name="href">mailto:<xsl:value-of select="staffEmailAddress"/></xsl:attribute>
                  <xsl:value-of select="staffEmailAddress"/>
                </a>
              </p>
            </xsl:if>          
          </div>
        </div>
        <!-- This doesn't display the thumbnail -->
        <xsl:if test="count(./* [@isDoc]) &gt; 0">
          <img src="{concat(substring-before(./*/staffProfileImage,'.'), '_thumb_225.jpg')}"/>
        </xsl:if> 
        <!-- This displays the full size image -->
        <xsl:if test="staffProfileImage != ''">
          <img alt="">
          <xsl:attribute name="src">
            <xsl:value-of select="staffProfileImage" />
          </xsl:attribute>   
        </img>
        </xsl:if>
        
      </li>
      </xsl:for-each>
    </ul>
  </div>


</xsl:template>

</xsl:stylesheet>