Seeds not sprouting

So I had germinated a few seeds and planted a few of them and they aren't sprouting. I had planted them as soon as the tap root split the shell, it's been a few days and I have my lights 18/6. I played 2 fingernails deep what did I do wrong???

how many days? i always plant as soon as the shell splits and it always takes a few days for the first root to grow down and take hold before they start heading upwards and breaking the surface

I gave up on germinating long ago. If a seed doesn't have the mojo to bust its shell and up through the dirt on its own... its probably not worth the energy of raising. (at least when you have limited space and need to make every plant count). Now I just plant them in a little cup in soil, water, give it some light and let nature do its thing.

Just let them be. Some pop up quick, others take longer. Make sure the soil is not too compact and is moist but not soaked.

Put the seed 1/4" deep, keep the soil only slightly damp not wet, and temp must be on the warmer side, 80 is ideal.
Also watch your soil choices, some are so hot with nutrients they kills seeds, and others are full of fungus gnat larvae which eat the shit out of seeds.
Don't go cheap on your soil.

I would imagine it depends on how deep you first plant them, I've had seeds take 6 days or more, agrevading as it is, but sometimes you have to have patients, of couse there's a limit to how long you're willing to wait.

Make sure the soil directly over the seed is light you don't want much resistance on it, to break the soil. One finger nail deep is plenty, if planted 2 deep they will take longer to pop the surface. If it were me I would probably lightly scratch some of the surface dirt away from the top of where the seed is. Keep it moist, don't overwater.
greensurfer is right temps are important, 75-80.
Good Luck