Did you run the command :update_navigator and/or restarted the emulator? Plus if im not mistaken FluxRP emulator the navigator shouldn't matter as its not useable as a user on the retro/rp.
INSERT INTO `items_base`(`id`, `sprite_id`, `public_name`, `item_name`) VALUES (ITEM_ID, SPRITE_ID, 'ITEM NAME', 'swfname')
Try using this as a base and make the SQLs yourself.