Needle Rotation

I have a line converted in to a movie clip. Am trying to rotate the line slowly. If i use something like

MyMC.rotation=30, the line instantly moves to the specified position. I tried using Transition Manager for the same.

transitionManager.start(MyMC, direction:Transition.OUT, duration:3, ccw:false, degrees:-30);

Although this shows the transition, the line disappears after rotating to the given angle. Why is this happeneing? How can I prevent this?