Adding a new Unit

Hello, i’ve tried adding the following code based on instructions found in CoreFunctions.php in order to add a new Unit for ingredients

add_filter( 'delicious_recipes_ingredient_units', 'add_measurements' );
	function add_measurements($measurements){
        $measurements['ff'] = array(
                'singular_abbr' => _x('φ','Φύλλο','delicious-recipes'),
                'plural_abbr'   => _x('φ', 'Φύλλα','delicious-recipes'),
                'singular'      => esc_html__('φύλλο','delicious-recipes'),
                'plural'        => esc_html__('φύλλα','delicious-recipes'),
                'variations'    => array( 'φλ', 'φλ.', 'φύλλο', 'φύλλα' ),
         );
        return $measurements;
     }

but without any results, i still can’t see my new unit

am i missing something?

Thanks for your time