Hi @Masud - thanks for joining TONMO - can you tell use more about your setup? Pics and any/all specs will be helpful for folks here who want to help. How small are the hatchlings? Perhaps they are too small for that kind of food?
Over and over we have found that brine shrimp will not sustain cuttlefish. The only continuously successful food for hatchlings has been live mysis (difficult to source and keep alive) for multiple daily feedings. There have been scattered reports of success with a mixture of pods but size and quantities are hard to judge. If you live near the shore and can do a daily plankton tow, this might suffice.
I have had some success keeping pregnant ghost shrimp and cherry shrimp in a floating basket with screen on the bottom. When the shrimps hatch they fall through the screen on the bottom, and the adults are not able to eat them. The baby shrimp do need to be well gutloaded, but I have had this work in conjunction with live mysis. And a few occasions where I was able to use only the hatched baby shrimp until the cuttles were able to eat adult ghost shrimp.
I haven't kept cuttlefish but I have kept a young inch-long arm span pygmy octopus. I fed him baby fish, which he liked more than ghost shrimp. Whenever he became a bit picky with his food I added some Seachem's GarlicGuard. It has a strong smell and makes the cabinet under my tank stink, but he usually ate much more when the GarlicGuard was added.
Good luck and I hope this helps!