Animator not animating a runtime instantiated child

I have a GameObject representing a room. As childs of this room I have 3 characters. Room has an animator component that control the synchronized animation of all characters.

The problem is I have another character that is instantiate from a prefab at runtime and this doesn't animate.

I tried several things:

 //NOT WORKING
 IEnumerator Start()
 {
     room.SetBool("e8", true);
 }

 //NOT WORKING
 IEnumerator Start()
 {
     room.Rebind();
     room.SetBool("e8", true);
 }

 //WORKING
 IEnumerator Start()
 {
     yield return new WaitForEndOfFrame();
     room.Rebind();
     room.SetBool("e8", true);
 }

The last try is working but the character looks stopped for an instant and suddenly jumps to the animation. I want the character animating from the beginning like the other characters.