Whereabouts do you put his bit of veg? I sometimes find if they are a bit cosy and hiding away a bit, it gives them incentive to go across the other side of the cage, if you put the veg separately on the other side of the cage. They know where to look for it each day and get in a routine. I started doing that with our first Syrian who NEVER wanted to come out of the cage - and often "nabbed" him on the way back after he'd nibbled his veg - by offering him a tube - or latterly just picking him up. Once he was out he was happy as larry but in his cage he just wanted to be left alone to do his own thing.