I think the issue is fixed, one must move the line with "create sequence na_items_item_id_seq cache 1;" just right before the function "create table na_items". This way the sequence will be available when PostgreSQL creates the table.
My News Aggregator's installation is working now :)
Please, let me know if I can do any other test just to verify if this issue is really fixed.
Thank you for your attention. Regards, Ricardo Jorge