I attribute failure to:
1) tank pollution/ammonia from over feeding to try to get them eatring.
2) lack of acceptance of prepared food due to being freshly imported and being obligate corallivores. I suspect that acceptance of prepared food is highly individualized.
If you do a few thread searches, and even check out fishbase, you'll see that they actually are not. I think it has more to do with handling until you have them.
How long did it take for yours to accept scallops. Did it nip or swallow the food in the beginning.
Did it accept pellets and other foods quickly?