mixing animations

I want to mix to different animations together but I don’t get it to work.
My Blender made character shall change a little during a spezial game state. So I added a keyframe, that only scales the head bone a little so the head of the character appears bigger. Then I still want to use all other animations with the character (like walking) just with the bigger head. so i put this (BigHead) Animation to a higher Layer (10) and enabled it. But I didn’t see anything change.
Then I tried the AddMixingTransform function which didn’t work either.
Can anyone tell me how to achive that?
can it be a problem, that i used LocRotScale Keys for all Bones on all the other animations?

Here are some Code Snipsets:

void Start () {
		boxBehaviour = gameObject.GetComponent<BoxBehaviour> ();
		rowdyBoxHead = animation["rowdy_box_layer"];
		animation["rowdy_box_layer"].wrapMode = WrapMode.ClampForever;
		//rowdyBoxHead.layer = 10;
		//rowdyBoxHead.wrapMode = WrapMode.ClampForever;
		rowdyBoxHeadTransform = transform.Find("Armature/Root/Root_001/Root_002");
	IEnumerator ActivateRowdyMode(){
		yield return new WaitForSeconds(60);		
		//rowdyBoxHead.enabled = true;
		//rowdyBoxHead.weight = 1.0f;
//		animation.CrossFade("rowdy_box_layer");

Hello there,

Using animations from a long dead project (and a couple minutes of try/fail), I created a script that did exactly what you want to achieve.
The names are a bit different, but you can get the general idea :wink:
It’s also written in js, but you should have no problem following the logic

var hip:Transform;

function Start() {
	animation["Run"].wrapMode = WrapMode.Loop;
	animation["Run"].layer = 1;
    animation["StandingAimDown"].wrapMode = WrapMode.ClampForever;
    animation["StandingAimDown"].layer = 1000; //above anything else
    yield WaitForSeconds(3);

This is tested and working.

Hope it helps,