Hittest from root timeline problem

this is my code:

if (_root.crosshare_mc.hitBox_mc.hitTest(_root.tree_mc.bird_mc)){
trace(“over bird”)
}

This is on frame 1 in the root timeline. I’m trying to detect a hit test between 2 movie clips, the crosshare_mc is being dragged, with the hitBox_mc being a smaller movieclip inside it.
The other movieclip is tree_mc with bird_mc being inside it.
I cannot get a hittest, can anyonr help me???