I've never had a problem seeding grass. I'm about the tackle a quite big area in the middle of my back garden that dips dramatically. I have accumulated a lot of topsoil from other projects. I'll sieve the soil to remove any weeds and large stones, press the soil in, using a plank of some sort. Once I think it's level I will put down seed, then sprinkle a thin layer of topsoil over the seeds. If it doesn't rain, water regularly in about 3 weeks the grass should be showing, after 6 weeks the area should be covered in lush green grass.