Not working on pages

Hi. This seems like a great plugin. However, I can’t seem to get it to work on pages. I’ve tried using the code you provided for this:
add_filter( ‘post_title_colors_post_types’, ‘ptc_on_pages’ );

function ptc_on_pages( $post_types ) {
$post_types[] = ‘page’;
return $post_types;
}
However, it doesn’t seem to be working for me. Help would be greatly appreciated.