Trigger not working in Postgres

Would some take a look at my trigger? It's not working and I don't understand why. There must be a syntax error somewhere.

CREATE OR REPLACE FUNCTION fn_parcels_compute_props() RETURNS trigger LANGUAGE plpgsql 
AS $$
begin
    new.lonlat := ST_Centroid(new.geometry);
    new.area := ST_Area((new.geometry)::geography);
    -- This value is present here in the `new` record. But that record is not 
    -- what is in the table after insertion. :<
    RAISE NOTICE 'area is ... %', new.area;
    return new;
  end
$$;

CREATE TRIGGER parcels_compute_props BEFORE INSERT
  ON parcels FOR EACH ROW EXECUTE PROCEDURE fn_parcels_compute_props();