Clearly this bird is afraid of your hand approaching it. Rather than bite you, the bird just flies away.
How big is the perch you use and how far away from the bird are you when you have it step on a perch? How close does your hand get before the bird flies away?
You probably have to condition the bird that your hand approaching means it gets a treat. Try this.. find the threshold of your bird's fear. Do this as a training session when your bird is a little hungry and a little motivated to earn treats. Put your hand out toward it and go as close as you can. Watch your bird's body language while you do this. Approach the bird with your hand as close as possible before the bird flies away, then take your hand away and give the bird a treat. Don't jerk your hand away too fast or you might scare the bird. Don't use a clicker but praise the bird if you want to. Repeat this lots and lots of times and just keep taking it further and further very slowly. As your bird gets used to it, move your hand a little closer and closer. This could take a few sessions over a few days, or maybe a couple weeks. If you push it too far and your bird flies away, it's counterproductive.
One last thing... never chase your bird with your hand. If the bird is communicating to you through it's body language that it doesn't want you to do it, then slowly pull your hand back and turn away from the bird. Since the bird should be a little hungry during this time, it lost an opportunity to get a treat and it lost attention from you. Then turn back to the bird and try again. Chasing the bird with your hand when it doesn't want to be near you will result in it flying away or biting you.
I described the same type of training process in this article already:
viewtopic.php?f=11&t=1528 but basically it's the same process of conditioning a bird to your hand being "nice" and "rewarding".