title: UIButton select state's image appears behind normal state's image
body: <p>I have a UIButton which has images set for both Normal and Selected State. From what I understand, when you switch the button.selected state to YES / NO, it should toggle between the two images. It sure does. But the selected state image always apear <strong>behind</strong> the normal state one. </p>
  
  <p>The reason I can see this is because my normal state is a play button and the middle triangle is basically transparent. I can see the pause button appear behind it.</p>
  
  <p>Anyone know what the problem is and, maybe how to fix it?</p>
  
  <p>Thanks :)</p>