I don't know how helpful this will be, but it worked for me to get my dumeril's to eat after a month and it's worth a try. Drop the f/t in the tank right before you go to bed, and completely cover the entire tank with a blanket and then check to see if he ate it in the morning.
Edit: I also did move him into a smaller tub from a glass aquarium 2 weeks before he finally ate, so being in a smaller enclosure could also have had an effect on him finally eating.