Plant eating can also be a sign that they need more hydration. But if still a young veil, he might just be hungry for more than just 10 crickets a day.
Whenever introducing a new (food item) it might take awhile for your chameleon to recognize it as food. Once he/she gets a taste, you'll probable get a quicker eating response.
I use them a handful of times each year. As hydration for crickets, roaches, and superworms. I just used/fed cantaloupe rinds last night to a few different roach species and the superworms.