ActionScript 3.0 :: Action Be Initiated Through Pressing A Key Combination?

Can an action be initiated through pressing a key combination? Here's a snippet instructing a MovieClip to move right when SHIFT+Z are pressed...

Code:
stage.addEventListener(KeyboardEvent.KEY_DOWN, testFn);
function testFn(event:KeyboardEvent){
if(event.keyCode == 16 && 90){
dot.x += 5;
}
}

Only the first key is recognized, i.e. the dot moves when SHIFT only or SHIFT+Z together are pressed; the swf's ignoring the second key.