use a custom view mode in node.tpl
$teaser is being passed in from template_preprocess_node().  DS just makes the view mode via a hook_entity_info; it doesn't wire it into the themeing system.  You need to do something like this:

function MYTHEME_preprocess_node(&amp;$variables) {
  $variables['custom_view_mode_one']
    = $variables['custom_view_mode_one'] == 'custom_view_mode_one';
}


You could also be smart by using a entity_get_info('node'), and get all of the view modes, and set similar variables.

Note that you should already have a variable called view_mode available in your template, too.