Hit test with score

Hi. I’m making a game at the moment that uses hit tests and scoring with varibles etc. Having a bit a problem with one of hit tests.

Basically the lives used variable is not working.

placed this on my asteroid mc that is gonna hit my space ship (arrow)

onClipEvent (enterFrame) {
speed = 10;
this._y += speed;
if (hitTest(_root.arrow)) {
root.lives = root.lives+1;

Any ideas…