Standard pet shop or bait shop crickets may be too large. Try to get crickets that are smaller than his head. Sub-adult crickets, maybe 1/2 " variety.

He might eat mealworms, although meal worms are kind of sluggish and may not catch his attention right away.

I'd try both and see what works. Once he starts eating you'll need to add some calcium with D3 powder. I use the product from RepCal.