There a few tricks to getting grass seed to take.
Get a soil test done and fertilize/lime according to the soil test results. After the fertilizer is watered in or rained in;
1) Don't plant grass seeds more than 1/4" deep. 1/8" is even better.
2) Get good ground to seed contact. After seeding roll with a lawn roller or cultepacker.
3) Get the seeds covered with straw or erosion blankets because of #4.
4) Every time the grass seed dries out, you lose 50% of the seeds.
5) While getting the grass germinated and established, frequent short waterings every day is much better than a soaking once a week. (that goes back to #4)
I just spent all day overseeding around a clients ponds where the grass was thin. I fertilized around the ponds last week, then they had 3" of rain. We're supposed to get rain in a few days. With the sun at a lower angle in the sky, and the cool nights with dew on the ground, that helps take the place of watering. It's not a complete substitute, but it helps. The ground isn't drying out now either, so that helps get the grass germinated too.
