I´m using this code to get translated my themes:
add_action('after_setup_theme', 'my_theme_setup');
function my_theme_setup(){
load_theme_textdomain('lc_realty', get_template_directory() . '/languages');
}
the files are named ru_RU.mo and ru_RU.po I have no problems with this code on versions 3.3.1 to 3.8.3 I will upgrade to 4.0 soon son I hope this continue working well.
Also I have this code to translate the plugins in admin panel
if ( is_admin() )
load_plugin_textdomain( 'myslider', false, 'myslider/languages' );