Depends.... The giants will not light up on the old portals unless they are getting a signal from the game. If you are playing the game without lights than something is wrong. If you just pushed the button on the portal with no game signal tis is normal.
there have been known issues with both figures and portals. This is why the new portal is worth the starter pack price. Its brighter and doesn't drain expensive batteries. When you're at the store, put your light up characters on the demo portal to make sure they light up.