Using "Match Filter" with eFORMz XML Data Node Variable

Can anyone help me with using the Match Filter function on Minisoft eFORMz.

I'm trying to select a specific node from an xml tree where the node name is repeated, using a child node as the selection criteria. It would seem to be what the match filter is supposed to do, but as I can't find any examples of how to use it, I'm rather stuck.

I've input XML data something like

<data>
  <entry>
    <filterValue>X</filterValue>
    <requiredValue>1</requiredValue>
  </entry>
  <entry>
    <filterValue>Y</filterValue>
    <requiredValue>2</requiredValue>
  </entry>
</data>

and I have the Data Node set to data/entry, the Node Filter set to requiredValue which seems to work ok, but as soon as I set the Match Filter to filterValue the variable returns nothing, even if I set the Match Value to *.

I'm assuming that there is some trick to how eFORMz is expecting these fields to be populated, but as I can't find any examples, I'm not sure what I'm missing. I've tried all the combinations of values I can thing of, but nothing returns anything if the Match Filter value is not empty.

Thanks for any ideas!