It's possible that the bulb did not produce the UVB needed for Calcium absorbtion. I'm not sure about the specs on that brand of bulb and I can't find any info on the net, after a quick search.

The bulb needs to be a 8% to 10% UVB bulb. Your timer for the bulb is right, 12 hr on 12 hr off. For heat, i use an overhead ceramic heater dialed in at about 95 degrees on one end of the enclosure (a 40 gal breeder tank lined w/newspaper). This way my beardy is able to self regulate his temp. I do provide a basking area under my UVB lamp that gets him within 6 to 8 inches of the bulb. I feed him dusted crickets, meal worms, pheonix worms(when I can afford them), and a veggie mix of turnip greens and collard greens.

I got my beardy in May. He was only about 5-6 inches long. Now he is pushing 12 inches or so, man these little guys grow fast.