Animation stops working after swapping.

I have a class which extends a SWC , in the swc i have two boxes, front and back and an animation on the same timeline. The animation works fine without swapping when I swap them the animation stops working. Anyway I can make it work?

I have the following code :

var frontTemp: DisplayObject = this.animationInstance.getChildByName("front");
var backTemp: DisplayObject = this.animationInstance.getChildByName("back");
this.animationInstance.swapChildren(frontTemp,back Temp);
this.animationInstance.gotoAndPlay("animation");