If the big adult cat got the food, the little one is probably very hungry by now. Maybe if you only set up the trap
when you see the little one around. Set the trap and move back away from it while the cat is drawn in by the tasty
aroma of fish or whatever. Then cover with a towel & bring him home. If it doesn't work, take the trap home & try
again later. Best of luck winning him/her over.

The spring trap hook sometimes can stick a bit & doesn't release the spring when they step on the metal plate.