I would think that for as dry as you think the soil is, there is still some moisture in it. The seed will absorb that moisture, trigger the response to germinate, then abort because there isn't enough moisture to continue.

I've grown grass for my cats many times, and usually use wheat/rye/oat berries and sow them about 1/4 inch below the soil surface.

If your seeds are all mixed up with the soil, are they close enough to the surface to sprout?