The thing about taming is that you need to win over his trust. Can I ask how he steps up onto your hand and perch?
When I went through the process with Niko, I started out with a plastic cup in which I put food. This was extended onto a perch or a stick to give me enough range to sit at a distance he was comfortable at while still being able to offer him food.
I got him used to the stick by having it by the cage and later in through the opening of the cage so that he would recognise it as 'food' and 'safe'. I then slowly moved closer with my hand, removed the stick and go to the stage where he ate out of my hand. The next stage was to offer him one seed at the time, so that I could progress to step-up which is the stage where you seem to be stuck at the moment.
This is where it stopped up a little, and training was a little slower. But what's important to remember is that all progress is progress and that a step back usually means three steps back. So don't rush it, take it at the speed of which your bird is comfortable and keep the training sessions short, so that you don't overstep and take those three steps back.
With time he will be more comfortable with you and you can start bonding outside of the cage. Birds are really sociable creatures, so once you earn some respect they seek you out when they're outside of the cage, simply for company. So try to read his body language as you approach the cage, stop if he shows any sign of stress or discomfort and keep up the training

It can be a timely exercise, but the reward is truly great!
Good luck!