get_post_meta doesn’t work

I created a custom meta box inside a page but I can’t display the content!
I’m inside the loop and here there is the code of my functions.php:

$meta_box['portfolio'] = array(
    'id' => 'descportfolio',
    'title' => 'Description',
    'context' => 'normal',
    'priority' => 'high',
    'fields' => array(
        array(
            'name' => 'Short Description',
            'desc' => 'This short desc will appear under the thumbnail with hover effect',
            'id' => 'portfolio_description',
            'type' => 'descport',
            'default' => ''
        )
   )
);  
add_action('admin_menu', 'descportfolio_add_box'); 
//Add meta boxes to post types
function descportfolio_add_box() {
    global $meta_box;

    foreach($meta_box as $post_type => $value) {
        add_meta_box($value['id'], $value['title'], 'descportfolio_format_box', $post_type, $value['context'], $value['priority']);
    }
}
//Format meta boxes
function descportfolio_format_box() {
  global $meta_box, $post;

  // Use nonce for verification
  echo '<input type="hidden" name="descportfolio_meta_box_nonce" value="', wp_create_nonce(basename(__FILE__)), '" />';

  echo '<table class="form-table">';

  foreach ($meta_box[$post->post_type]['fields'] as $field) {
      // get current post meta data
      $meta = get_post_meta($post->ID, $field['id'], true);

      echo '<tr>'.
              '<th style="width:20%"><label for="'. $field['id'] .'">'. $field['name']. '</label></th>'.
              '<td>';
      switch ($field['type']) {
          case 'text':
              echo '<input type="text" name="'. $field['id']. '" id="'. $field['id'] .'" value="'. ($meta ? $meta : $field['default']) . '" size="30" style="width:97%" />'. '<br />'. $field['desc'];
              break;
          case 'descport':
              echo '<input type="textarea" name="'. $field['id']. '" id="'. $field['id'] .'" value="'. ($meta ? $meta : $field['default']) . '" size="30" maxlength="5" style="width:97%" />'. '<br />'. $field['desc'];
              break;
          case 'textarea':
              echo '<textarea name="'. $field['id']. '" id="'. $field['id']. '" cols="60" rows="4" style="width:97%">'. ($meta ? $meta : $field['default']) . '</textarea>'. '<br />'. $field['desc'];
              break;
          case 'select':
              echo '<select name="'. $field['id'] . '" id="'. $field['id'] . '">';
              foreach ($field['options'] as $option) {
                  echo '<option '. ( $meta == $option ? ' selected="selected"' : '' ) . '>'. $option . '</option>';
              }
              echo '</select>';
              break;
          case 'radio':
              foreach ($field['options'] as $option) {
                  echo '<input type="radio" name="' . $field['id'] . '" value="' . $option['value'] . '"' . ( $meta == $option['value'] ? ' checked="checked"' : '' ) . ' />' . $option['name'];
              }
              break;
          case 'checkbox':
              echo '<input type="checkbox" name="' . $field['id'] . '" id="' . $field['id'] . '"' . ( $meta ? ' checked="checked"' : '' ) . ' />';
              break;
      }
      echo     '<td>'.'</tr>';
  }

  echo '</table>';

}
// Save data from meta box
function descportfolio_save_data($post_id) {
    global $meta_box,  $post;

    //Verify nonce
    if (!wp_verify_nonce($_POST['descportfolio_meta_box_nonce'], basename(__FILE__))) {
        return $post_id;
    }

    //Check autosave
    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {
        return $post_id;
    }

    //Check permissions
    if ('page' == $_POST['post_type']) {
        if (!current_user_can('edit_page', $post_id)) {
            return $post_id;
        }
    } elseif (!current_user_can('edit_post', $post_id)) {
        return $post_id;
    }

    foreach ($meta_box[$post->post_type]['fields'] as $field) {
        $old = get_post_meta($post_id, $field['id'], true);
        $new = $_POST[$field['id']];

        if ($new && $new != $old) {
            update_post_meta($post_id, $field['id'], $new);
        } elseif ('' == $new && $old) {
            delete_post_meta($post_id, $field['id'], $old);
        }
    }
}

add_action('save_post', 'descportfolio_save_data');

And here my code inside the page

<?php echo get_post_meta($post->ID, "descportfolio", true); ?>

I’ve tried with get_post_ID instead of $post->ID, but nothing changed.
Can anyone see any error?