rbugatell

Hola, muchas gracias por responder, la verdad es que estamos un poco desesperados lo hemos provado todo y sigue sin funciona, ahora ya no sale el mensaje de error, erpo los cambios en nuestro child theme no se hacen efectivos en el blog, y si los hacemos en el tema padre si.
Te escribo la cabecera de mi child theme a ver si tu nos puedes ayudar:

La cabecera de mi tema hijo es esta, siendo «Template: twentyeleven» la carpeta donde se aloja el tema padre en nuestro /wp-content/themes/twentyeleven
/*
Theme Name: childtheme
Theme URI: http://behind2glasses.com
Template: twentyeleven
Author: Tell Rose and Leru Ben
Author URI: http://behind2glasses.com/
Description: The 2011 theme for WordPress is sophisticated, lightweight, and adaptable. Make it yours with a custom menu, header image, and background — then go further with available theme options for light or dark color scheme, custom link colors, and three layout choices. Twenty Eleven comes equipped with a Showcase page template that transforms your front page into a showcase to show off your best content, widget support galore (sidebar, three footer areas, and a Showcase page widget area), and a custom «Ephemera» widget to display your Aside, Link, Quote, or Status posts. Included are styles for print and for the admin editor, support for featured images (as custom header images on posts and pages and as large images on featured «sticky» posts), and special styles for six different post formats.
Version: 1.4
License: GNU General Public License v2 or later
License URI: http://www.gnu.org/licenses/gpl-2.0.html
Tags: dark, light, white, black, gray, one-column, two-columns, left-sidebar, right-sidebar, fixed-width, flexible-width, custom-background, custom-colors, custom-header, custom-menu, editor-style, featured-image-header, featured-images, full-width-template, microformats, post-formats, rtl-language-support, sticky-post, theme-options, translation-ready
Text Domain: twentyeleven
*/

Gracias de nuevo, esperamos tu respuesta 🙂