Changing UIImageView Image

[JRuc33]

- (IBAction)touch_btnAdvice:(UIButton *)sender {
        UIImage	*aceC = [UIImage imageNamed: @"black.png"];
	[pPic10 setImage: aceC];
}

I want to switch a UIImageView Image from one image to another when I press a button. What is wrong with this code segment, cuz its not working. I have a image named black.png in my project.