give him time. my GSP didnt eat for ages after i put him in the tank. i didnt have access to Ghost shrimp or other live foods. so i tried frozen seafoods, frozen bloodworm, dried krill ect. he didnt wanna take anything at first, but he got hungry.
spot feeding helps. but remember to take out any food that doesnt get eaten so it doesnt mess your water up. also feeding with the lights off. or even going out of the room will also help. if you want to stay and watch. sit away from the tank and keep still. GSP's have great eyesight.
sooner or later yours will eat... and they learn quickly who feeds them. its just a matter of time.