Hey all - this question seems fairly similar to the question at XSLT nodeset question, but that one's a year old and doesn't really answer my question.

I'm trying to pass a set of nodes (actually just one in this case) from one template to another template, using xsl:call-template. But I keep getting "expression must evaluate to a node-set". I'm using msxsl:node-set() to try and convert my "select" into a node set. In this case I could just pass through an id and use that to reinstantiate the (single) node on the other side, but I'd like to know how to do this since there are other cases in my code where I want to pass through more than one node. Any help would be greatly appreciated. :)

SideNavigation.xslt:

<?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:msxsl="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 msxsl umbraco.library Exslt.ExsltCommon Exslt.ExsltDatesAndTimes Exslt.ExsltMath Exslt.ExsltRegularExpressions Exslt.ExsltStrings Exslt.ExsltSets ">

    <xsl:include href="SideNavigation_PrintChildren.xslt"/>

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

    <xsl:param name="currentPage"/>

    <xsl:variable name="sectionTopNode" select="$currentPage/ancestor-or-self::* [@level=2]" />
    
    <xsl:template match="/">

        <xsl:call-template name="SideNavigation_PrintChildren">
            <xsl:with-param name="printChildrenOf" select="msxsl:node-set($sectionTopNode)" />
        </xsl:call-template>
        
    </xsl:template>

</xsl:stylesheet>

SideNavigation_PrintChildren.xslt:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:msxsl="urn:schemas-microsoft-com:xslt"
    exclude-result-prefixes="msxsl">
    <xsl:output method="xml" indent="yes"/>
    <xsl:param name="printChildrenOf" />
        <xsl:template name="SideNavigation_PrintChildren">
        <ul>
            <xsl:variable name="children" select="$printChildrenOf/* [@isDoc]" />
        </ul>
    </xsl:template>
</xsl:stylesheet>