yep , as Rosemary said , fresh seed is a must with parsnips . Germinatation really falls off the older the seed is. They also take a very long time to germinate, 3-4 weeks is the norm, but 5 or a bit more is also possible. They should really have been sown much earlier , winter/early spring depending on weather. However, you could still get a good crop just a little later thats all. Remeber also to treat them a bit like carrots , no fresh manure (they will fork). Try to get the soil as stone free as possible also. Good luck with them anyway ....
Russ