It could be too that some of the calis are still in breeding mode. My males are still being finicky. Don't sweat it, they will come around. A couple things to try though.
Try feeding in the evening, as they are more active at that time anyhow.
If feeding live try a hopper and then follow up with a F/T Adult mouse or rat pup.
Good luck,, but don't panic, he will come around, they always do.
Cheers
Jim