What next?

My IRN, Tiki, will take treats from my fingers inside and outside of his cage, but when I try to get him to step up, he squawks and flies away. After a bit of flying around, I can get him to step up and return him to his cage. How can I get him to step up willingly? I do not try inside his cage, because his body language shows that is not a good idea. He has come such a long way, but I am ready to work on the next step.
~Sherri