remove array when touch a movieClip (hitTestObject)

Hi all,

I'm making an AS3 platform game.

My player can shoot bullets. If a bullet touch an enemy, it will be removed.

for (var j:int = 0; j < bulletList.length; j++) // for each bullet in the bulletList
  {
  if (enemies.mc.hitTestObject(bulletList) ){
  trace("Bullet and Enemy are colliding");
  enemyDie(i)
  bulletList.removeSelf();
  }

But now I'd like to remove the bullet if it touch a movieClip on the stage (with the instance "tree_mc"). And I can't figure out how to do so...

I've tried this :

var tree_mc;
for (var j:int = 0; j < bulletList.length; j++){
if(tree_mc.hitTestObject(bulletList)){
  trace("bullet hit tree");
  }

But it's not working.

Do you know how I can do that ?

Thank you