If people are having trouble with seeds germinating you can use gibberellic acid (GA-3) to force the germination of troublesome seeds. It can be difficult to use, needing only an amazingly dilute amount and it will always stretch your seedlings initially but if your in real need, us it.
http://www.super-grow.biz/Products.jsp sells it dirt cheap, use only a few grains per liter of water and using something like liquid-karma or Nitrozime with it will also help. Gibberellic acid has been used to germinate seeds over 1000 years old from extinct species! It is THE Hormone that signals seed germination.
There have also been issues with X-RAY exposure to seeds causing them to fail before germination, I talked with a plant physiology professor about this and it was confirmed that yes, x-rays can damage the embryonic cells of a seed, it may not be an issue of poor seed quality.