ActionScript 3.0 :: Flash Losing Key Press Detecting When Button Is Clicked?

i'm building an projector application in AS3, as a slide show.When the right and left keys are pressed on the keyboard, the slides change.the code to change the slide:

Code:
function setup() {
stage.addEventListener(KeyboardEvent.KEY_DOWN, displayKey);
}
setup();

[code]....

Some slides have button on it, that change the slide, jumping to a chapter the user whant to see.the problem i'm having is that when the button at a slide is clicked, the key press detection does not work anymore. To make it work, I have to click somewhere on the stage.