If they crack but don't grow a taproot, look out for fungus as your culprit.

You can try sterilizing everything first... even rinse the seeds in 10% bleach... then rinse them off again really well with tap water.

If you use the water method, there should be enough water just to moisten the seeds but not cover them! I like the glass tubes that fine cigars come in...just a splash of water... add seeds... lay on its side in a warmish (between 75 and 85 deg F, no warmer!) place and I get taproots in less than 24h. Usually... some strains take longer.