How old are your beardies?
Juveniles tend to not eat as much greens. they need more protein in their diet and way more insects than greens. Keep feeding them dusted insects every day while offering greens anyways.
Eventually they will start to eat the salads.
I did however, get mine to start eating more by hand feeding them greens (careful with this cause then they get lazy and expect it all the time) or try putting some wax worms or silworms under the salad so that it moves a little and they think its alive)
anything else to do with nutrition I would check out www.beautifuldragons.com possibly the best and most complete website for beadie nutrition and general health
Derek