Page part locations does not appear anywhere in the admin

Hi Again,
I added this code in the functions.php file, but I see nothing in the admin screens:
I don’t have a way to select the location of each page part, I don’t even see a location column in the page-part table.
what am I doing wrong?

function my_page_parts_locations( $locations, $post_type ) {

// Page Locations
if ( ‘page’ == $post_type ) {
$locations[] = ‘left column’;
$locations[] = ‘right column’;
$locations[] = ‘sidebar’;
}

// Post Locations
if ( ‘post’ == $post_type ) {
$locations[] = ‘left column’;
$locations[] = ‘right column’;
$locations[] = ‘sidebar’;
}

return $locations;

}
add_filter( ‘page_parts_locations’, ‘my_page_parts_locations’, 10, 2 );