I'm stuck with an XPath query to produce a TreeView.

From the data below, I want to select all the score elements having an IdIn
of 2018, ***including their ancestors***.
With the result, I want to fill a TreeView control.

This is my simplified data:

<?xml version="1.0" encoding="utf-8"?>
<Punten>
 <test Titel="TRAINING" >
   <test Titel="web" >
     <test Titel="Excel" >
       <test Titel="Eindtest Excel" >
         <score IdIn="1878" Score="12" />
         <score IdIn="2011" Score="14" />
         <score IdIn="2018" Score="15" />
       </test>
     </test>
     <test Titel="VB" >
       <test Titel="TEST1" >
         <score IdIn="2127" Score="20" />
         <score IdIn="2018" Score="17" />
         <score IdIn="2037" Score="11" />
       </test>
     </test>
     <test Titel="ASP" >
       <test Titel="Examen" >
         <score IdIn="1878" Score="28" />
         <score IdIn="2011" Score="-998" />
         <score IdIn="2018" Score="60" />
       </test>
     </test>
   </test>
   <test Titel="web2" >
     <test Titel="Excel" >
       <test Titel="Eindtest Excel" >
         <score IdIn="2042" Score="13" />
         <score IdIn="2091" Score="12" />
         <score IdIn="1818" Score="13" />
       </test>
     </test>
     <test Titel="Flash" Soort="Vak" >
       <test Titel="flintstones" >
         <score IdIn="2091" Score="6" />
         <score IdIn="2087" Score="10" />
         <score IdIn="2123" Score="5" />
       </test>
     </test>
   </test>
 </test>
</Punten>

This is the tree I want to produce (the scores with IdIn=2018):

<Punten>
 <test Titel="TRAINING" >
   <test Titel="web" >
     <test Titel="Excel" >
       <test Titel="Eindtest Excel" >
         <score IdIn="2018" Score="15" />
       </test>
     </test>
     <test Titel="VB" >
       <test Titel="TEST1" >
         <score IdIn="2018" Score="17" />
       </test>
     </test>
     <test Titel="ASP" >
       <test Titel="Examen" >
         <score IdIn="2018" Score="60" />
       </test>
     </test>
   </test>
 </test>
</Punten>

I have tried this XPath value (with an XmlDataSource):
//score[@IdIn='3234']/ancestor-or-self::*

It should give me what I want, but it produces an error in
TreeView.DataBindRecursive:
Object reference not set to an instance of an object

The query
//test[not(@Verwijderd='1')]/score[@IdIn='3234']
works without an error, but only produces the "scores" items

Does anybody know a working XPath query for this?

Any help with this problem is appreciated.

--

Riki