I had 3 of 4 seeds crack in a day or two day by putting them in water until they sank when pushed lightly, then into some wet paper towel in an unzipped baggy in the cupboard. I should check on the 4th tonight, but I have a feeling it'll take another day or two.

For my current grow we had nearly all of 20-something seeds germ using just paper towels. I think maybe 2-3 of them didn't go. I like the paper towel method because it works for me so far.

Could it just be the seeds? Sounds like you did everything correctly.