Hey,
Make sure that they are able to find the food easily, and that it is very tiny, like a fine powder. What I do is put some flakes into a small bag, and crush that up as much as possible. They will not eat anything that will not fit into there mouths easily (if they spit it back out then it is still to big for the fry to swallow). Also what I do is keep my fry in a breeding net for the first 3-4 days to make sure that they are able to find food easily, also so I can clean up the extras without any trouble.
If they are in a big tank with other fish, they are trying to hide in the gravel, if they are in there own tank then I am not certain waht they are doing. I keep my fry in a 5 and 10 gallon bare bottom tanks so I have not experienced this myself.
Also, if they are in a big tank, they may not be eating because it mgiht be hard for them to find or see the food. My fry also love baby brine shrimp (i just use the frozen stuff).
Good luck with your new fry, I'm sure they will start eating.