Hello,
How old is your little baby & how big/long is he? You can post pictures so we can see him.
Are the crickets you are feeding, smaller than the space between the eyes?
You could try small dubia roaches, small silkworms, phoenix or calcium worms are all good choices.
Which greens have you tried? Many times, the babies & youngsters tend not to show a lot of interest in them initially but keep trying. Eventually he will recognize the greens as a food source!
Are you using a good UVB source & supplementation for him?
How are the temperatures in his tank for him?
Tracie