$output .= '<li class="recentcomments">' . sprintf(_x('%1$s %2$s - %3$s %4$s', 'thst'), get_avatar( $comment, 48 ), (...);
This is my line of code and Wordpress Theme Checker tells me "Text domain problems. You have not included a text domain!" I have included one though, as you can see. What could be the problem here?