Can you easily get pod cultures from either local hobbyists or from the local fish store? If so you could put a few cultures of those in the tank and do so regularly until you can bolster the resident population enough to sustain the dragonette, and while its hunting and eating those pods you can continue to supplement with frozen offerings like enriched brine, mysis, and rotifers and eventually it should get used to and take those frozen offerings. Even if it seems like there's enough pods in the tank to sustain these fish its a good idea to reload with pods regularly as mandarins eat a ton and can wipeout a population quickly. How big is the aquarium? Do you have a refugium tied into it?