getting issue with custom advance fields plugin

EDIT:
(Just had another look at the documentation, and noticed the following)

If you look at the code below, you’ll notice that you’re doing it differently. They are calling the field from within a group.

$miembros = get_group('miembro');
  // to see how this made the arrangement can use pr($miembros);
  // the way this arrangement is made
  // [index of the group] [field name] [index of the field]
  // for fields image type level but in accordance with the letter "o" to the original image or "t" for thumbnail
  foreach($miembros as $miembro){
    echo $miembro['nombre_miembro'][1]."<br />";
    echo $miembro['puesto_miembro'][1]."<br />";
    echo "<img src="".$miembro["foto_miembro'][1]['t']."'><br /><br />";
  }

So, what you need to do it put the Released field into it’s own group (as an example, let’s call it group1), and then do the following:

$group = get_group('group1');
 foreach($groups $group){
    echo $group['released'][1];
}

The function needs you to specify the individual fields before calling them, so that you ca choose which ones to do.

(Side note: If you continue to have troubles with this plugin, I would recommend trying out Advanced Custom Fields instead, as the user interface and the code for showing field content in templates is a lot easier to understand.)