RTFM - решение 90% всех проблем

"INSTALL_QUICKSTART.txt" wrote:

3. Add the following four lines of code to your settings.php file:

/**
* Add the domain module setup routine.
*/
include DRUPAL_ROOT . '/sites/all/modules/domain/settings.inc';

NOTE: You may need to alter the file path above based on your
site configuration. See INSTALL.txt for further help.

IMPORTANT: You must add these lines to settings.php after the
$databases. Normally, you should add these lines to the end of the
settings.php file.

NOTE: If you perform a Drupal core version upgrade, you must
remove these lines from settings.php. See UPGRADE.txt for details.