MovieClip did not play animation when using addChild()

Question

i am trying to make a simple flash game.

And I've been searching about this problem but I can't found any questions/answers that helped me, so here it is:

I am trying to use addChild() to generate the pokemon Movieclips

    var comPkm:MovieClip = new bulbasaur;
    comPkm.x = 620;
    comPkm.y = 270;
    comPkm.height = 80;
    comPkm.width = 77;
    addChild(comPkm);
    comPkm.gotoAndPlay("idle");

the problem is: The "idle" stance for the pokemon does not play at all.
But, if I put the pokemon directly to the timeline it would work. Any idea what's wrong and what's the solution? Thanks :)

Answer 1

Unfortunately, setting some properties of a MovieClip causes the clip to not play an animation. Setting x, y, height, or width break a timeline animation. The silent failure without so much as a trace message confounded me several times. A workaround is create a parent placeholder and have the ActionScript modify parent or child. Example:

comPkm.parent.x = 620;
comPkm.parent.y = 270;
comPkm.parent.height = 80;
comPkm.parent.width = 77;

Related: Scaling onstage MovieClip w/ "scaleX" breaks timeline animation ...really?

If you modify any of the following properties of a MovieClip object that contains a motion tween, the playhead is stopped in that MovieClip object: alpha, blendMode, filters, height, opaqueBackground, rotation, scaleX, scaleY, scale9Grid, scrollRect, transform, visible, width, x, or y. However, it does not stop the playhead in any child MovieClip objects of that MovieClip object.

http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/display/MovieClip.html

In my experience, the playhead is permanently broken, ignoring future calls to gotoAndPlay.