movie clip button requires two clicks to activate

Hi. Is there any reason why my movie clip buttons require two clicks to active the toggle function?

I dont understand why this is happening.

My code:

btn_radio.addEventListener(MouseEvent.MOUSE_UP, ToggleRadio);

btn_radio.buttonMode = true;
btn_radio.useHandCursor = true

function ToggleRadio(myEvent:MouseEvent) {
if(!btn_radio.toggle){
  btn_radio.gotoAndStop("up");
  }
else
{
  btn_radio.gotoAndStop("down");
  }
  btn_radio.toggle=!btn_radio.toggle;
  }

Any help would be great.

- Pat