You could check if the turret has anything to shoot with the turret hasTarget event. like this,
If Not hasTarget >> bow.angle = 0;
the problem is, turret/bow is always has target. And I can't invert onShoot condition. what if the bow.angle=0 but the Box going to left-down overtime? Or do I need to remove turret behavior? I just need to figure out how to set angle when bow not onShoot mode.. thanks for reply BTW