theme_websnapr_field_formatter

Just to rule out caching issues, I tried overriding a theme function from CCK, and that worked fine. So it really does seem to be specific to this module: I can't override theme_websnapr_field_formatter.

function phptemplate_websnapr_field_formatter($element) {
  drupal_set_message("Lucy, I'm home!");
  if ($element['#item']['url']) {
    return websnapr_field_field_formatter($element['#field_name'], $element['#item'], $element['#formatter'], $element['#item']['url'], $element['#node']->title);
  }
}