It seemed like we tried EVERYTHING good as a reward for our quaker and nothing worked until I discovered her love for roasted chicken (grocery store kind) and swiss cheese. She will do anything for chicken especially. Good luck and just keep trying until you find something your baby loves!
Alot of time I find that a picky bird is more the situation of a full bird try cutting back on the amount of food left in his cage all day (I leave dry pellets in the cage all day so they have something to eat ) but when I get home I share the good stuff, most of the training videos say the same thing it's hard to get a full contented bird do do anything for a treat but if he's feeling a little hungry he might be interested in what you've got.
I agree...pellets only in the dish and experiment with treats. Our IRN loves cashews (organic roasted, no salt) and pistachios (same). Such changes in her recently...she actually flies TO ME when I ask. She's a love and a queen of the birdroom! Good luck!