How can i approach my cockatiel

[Wolf]

Try it with treat in same hand as you ask her to step up on. Just don't give the treat unless she at least comes to hand.

[cockatiels15P]

She still runs away

[Wolf]

Does Tina still step up while in the cage?

[Wolf]

Excuse me for having bad manners. It is good to hear from you again.
Are you working with Tina in the small cage or is she back in the large one? When you let her out for her free time ( not training ) is she with the other bird or not?
It has been a while since our last conversation so if you could bring me up to speed on where we are at the present time, it would help me answer you. I don't know if you have made any even temporary progress or if Tina has reverted to previous behaviors. It is not uncommon to be making progress and then the bird relapses back a step or two if we make a small mistake. Either way it's not a big deal patience and perseverance will pay off in the long run.
The thing that I am seeing is that Tina is not yet trusting you and that is the most important, the most rewarding and the most difficult step to accomplish.