Oh man, it's coz you're not using ZooMed, that's why. He's not a tortoise is he? He'll eat once his shell grows in...j/k
but in all seriousness, it might take a few weeks, or, with many of these guys it's preference. Right now if you're giving him enough of the things he *prefers*, then he's obviously going to eat all that stuff first, and leave the things he doesn't prefer. But if you really want him to get on this diet bad, start changing the ratios until you cross the line where his hunger>preference.