[flexcoders] xml E4X adding a child?

[flexaustin]

So if I have this XML:

<node id="24836">
  <data key="name">
    name24836
  </data>
  <data key="blah"/>
  <data key="type">
    null
  </data>
  <data key="isbb">
    false
  </data>
  <data key="groups">
    <group name="Address"/>
  </data>
</node>

How do I add another group? The following doesn't work?

xmlData.insertChildAfter( xmlData.(elements('data').(attribute('key') == 
'groups')).group[0], <group name="generic"/> );