Radiobutton callback not working...

I am trying to change the visibility of controls in a window when the user clicks one of two radio buttons using the following callback functions. However, nothing happens when I click the radio buttons. I have also tried the onChange and onChanging events in addition to onClick with the same result. What am I doing wrong? Thanks.

function radioDoubleMatOnClick() {

  if (radioDoubleMat.value == true) {

  if (!patternIsInstalled(PATTERN_0)) outerMatPatternGroup.hide();

  innerMatPanel.show();

  }

}

function radioGlowOnClick() {

  if (radioGlow.value == true) {

  outerMatPatternGroup.hide();

  innerMatPanel.hide();

  }

}

radioDoubleMat.onClick = radioDoubleMatOnClick ();

radioGlow.onClick = radioGlowOnClick ();