Why is my UIButton object don't change origin?

Why is my UIButton object don't change origin?

I create bytton: IBOutlet UIButton *but; and connect it with my xib
button. But when I set origin to my button:
but=[[UIButton alloc] init];
[but setFrame:CGRectMake(50, 100, but.bounds.size.width,
but.bounds.size.height)];
Origin of my button don't change. Wat is reason of it? And How I correct it?