This question has been answered by BobRay. See the first response.
$fields = array( 'username' => $name, 'sitename' => $siteName, 'activationURL' => $activeURL, 'deactivationURL' => $deActiveURL, );
$fullName = $profile->get('fullname'); $fields = array( 'fullname' => $fullName, 'username' => $name, 'sitename' => $siteName, 'activationURL' => $activeURL, 'deactivationURL' => $deActiveURL, );