We have two Bearded Dragons. One we have had since hatchling(Harry) and one since about 1 year old(Harold). Harold was very into crickets when we first got him and would not eat his greens either. Harry has always loved greens(her favorite are dandelions{buds and leaves}) After we put them together, we noticed that Harry would run over and eat the greens right away and as soon as Harold saw that Harry was eating, he would come to the dish and eat too. If you have any other dragons why not try putting them next to each other with their dishes put up against the sides facing each other. If one is eating it might stimulate the other to give it a try.
harold