I have this xslt that are generating a course list. but I can not get it to sort list against a field I have added on the document type which I have called "sortOrder".The "sortOrder"field is of the type numeric. My code can be viewed below:

<?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"
    exclude-result-prefixes="msxml umbraco.library">


  <xsl:output method="xml" omit-xml-declaration="yes" />
  <xsl:param name="currentPage"/>
  <!-- Don't change this but create a 'number' element in your -->
  <!-- macro with the alias of 'numberOfItems' -->
  <xsl:variable name="numberOfItems" select="500"/>
  <xsl:template match="/">
    <!-- The fun starts here -->
    <xsl:if test="$currentPage/@id = 1299">
Kurser
      <ul style="padding:0px">
        <xsl:for-each select="umbraco.library:GetXmlNodeById(1299)//node[@nodeTypeAlias='IIHKursus']">
          <xsl:sort select="@sortOrder" order="descending"/>
          <xsl:if test="position() &lt;= $numberOfItems">
            <li>
              <xsl:value-of select="parent::node/@nodeName"/>
              <br/>
              <a href="{umbraco.library:NiceUrl(parent::node/@id)}">
                <xsl:value-of select="@nodeName"/>
              </a>
            </li>
          </xsl:if>
        </xsl:for-each>
      </ul>
    </xsl:if>
  </xsl:template>
</xsl:stylesheet>