problem with key

I am trying to upconvert from a flat-file. After I get it into XML form I
try to add hierarchy using "key".
-------------
OUTPUT
-------------
I get NO results from
<SubPossibilities>
            <xsl:copy select="key('SemanticDomainByParent', '$parentSD')"/>
</SubPossibilities>

so output looks like
<SubPossibilities/>

So what am I doing wrong?


Starting with this XML
-------------
XML input
-------------

...      <Possibilities>
         <CmSemanticDomain level="1"      sd="1"   parent=""
guid="I63403699-07C1-43F3-A47C-069D6E4316E5">
            <line tag="sd">Universe, creation</line>
            <line tag="gd">I63403699-07C1-43F3-A47C-069D6E4316E5</line>
         </CmSemanticDomain>
         <CmSemanticDomain level="2"  sd="1.1"   parent="1"
guid="I999581C4-1611-4ACB-AE1B-5E6C1DFE6F0C">
               <line tag="sd">Sky</line>
               <line tag="gd">I999581C4-1611-4ACB-AE1B-5E6C1DFE6F0C</line>
          </CmSemanticDomain>
         <CmSemanticDomain level="3"   sd="1.1.1"    parent="1.1"
guid="IDC1A2C6F-1B32-4631-8823-36DACC8CB7BB">
            <line tag="sd">Sun</line>
            <line tag="gd">IDC1A2C6F-1B32-4631-8823-36DACC8CB7BB</line>
         </CmSemanticDomain>
         <CmSemanticDomain level="4"  sd="1.1.1.1"    parent="1.1.1"
guid="I1BD42665-0610-4442-8D8D-7C666FEE3A6D">
            <line tag="sd">Moon</line>
            <line tag="gd">I1BD42665-0610-4442-8D8D-7C666FEE3A6D</line>
         </CmSemanticDomain>
         <CmSemanticDomain level="4"  sd="1.1.1.2"  parent="1.1.1"
guid="IB044E890-CE30-455C-AEDE-7E9D5569396E">
            <line tag="sd">Star</line>
            <line tag="gd">IB044E890-CE30-455C-AEDE-7E9D5569396E</line>
         </CmSemanticDomain>
         <CmSemanticDomain level="4"  sd="1.1.1.3"   parent="1.1.1"
guid="IA0D073DF-D413-4DFD-9BA1-C3C68F126D90">
            <line tag="sd">Planet</line>
            <line tag="gd">IA0D073DF-D413-4DFD-9BA1-C3C68F126D90</line>
         </CmSemanticDomain>

...
-------------
XSL
-------------
...
  <xsl:key name="SemanticDomainByParent" match="CmSemanticDomain"
use="@parent" />

    <xsl:template match="CmSemanticDomain">
        <CmSemanticDomain>
            <xsl:apply-templates select="@* | node()"/>
            <xsl:apply-templates
select="key('SemanticDomainByParent',@sd)"/>
        </CmSemanticDomain>
    </xsl:template>

    <xsl:template match="line[@tag='gd']">
        <xsl:variable name="parentSD" select="parent::*/@parent"/>
        <SubPossibilities>
            <xsl:copy select="key('SemanticDomainByParent', '$parentSD')"/>
        </SubPossibilities>
    </xsl:template>

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


-------------
Desired OUTPUT
-------------
...
      <Possibilities>
         <CmSemanticDomain level="1"      sd="1"   parent=""
guid="I63403699-07C1-43F3-A47C-069D6E4316E5">
               <line tag="sd">Universe, creation</line>
               <SubPossibilities>
                  <CmSemanticDomain level="2"  sd="1.1"   parent="1"
guid="I999581C4-1611-4ACB-AE1B-5E6C1DFE6F0C">
                       <line tag="sd">Sky</line>
                      <SubPossibilities>
                          <CmSemanticDomain level="3"   sd="1.1.1"
parent="1.1"    guid="IDC1A2C6F-1B32-4631-8823-36DACC8CB7BB">
                              <line tag="sd">Sun</line>
                              <SubPossibilities>
                                  <CmSemanticDomain level="4"
sd="1.1.1.2"  parent="1.1.1"  guid="IB044E890-CE30-455C-AEDE-7E9D5569396E">
                                      <line tag="sd">Star</line>
                                  </CmSemanticDomain>
                                  <CmSemanticDomain level="4"
sd="1.1.1.3"   parent="1.1.1"
guid="IA0D073DF-D413-4DFD-9BA1-C3C68F126D90">
                                       <line tag="sd">Planet</line>
                                 </CmSemanticDomain>
...
                             </SubPossibilities>
                         </CmSemanticDomain>
                      </SubPossibilities>
                  </CmSemanticDomain>
              </SubPossibilities>
          </CmSemanticDomain>
      </Possibilities>


Jim Albright
Wycliffe Bible Translators
704-562-1529