Animation Additive not working

What can cause animation additive not working ?

I have 3 files - idle, walk and shoot that I exported them from blender.

I did layer them and still not work. it's not add the shoot animation to either idle or walk. Please help

Code (JavaScript):

1.  
2.  
3. function Start () {
4.  
5.  
6.  
7.     ani[animationidle.name].layer = 2;
8.  
9.     ani[animationidle.name].enabled = true;
10.  
11.  
12.  
13.     ani[animationwalk.name].layer = 2;
14.  
15.     ani[animationwalk.name].enabled = true;
16.  
17.  
18.  
19.     ani[animationshoot.name].layer = 4;
20.  
21.     ani[animationshoot.name].weight = 1;
22.  
23.     ani[animationshoot.name].blendMode = AnimationBlendMode.Additive;
24.  
25.     ani[animationshoot.name].enabled = true;
26.  
27.  
28.  
29. }
30.  
31.  
32.  
33. function Update () {
34.  
35.  
36.  
37.  
38.  
39.         if (leftJoystick.IsFingerDown())
40.  
41.             ani.Play(animationwalk.name);
42.  
43.         else
44.  
45.             ani.Play(animationidle.name);
46.  
47.          
48.  
49.         if (rightJoystick.IsFingerDown()) {
50.  
51.             ani[animationshoot.name].enabled = true;
52.  
53.         }
54.  
55.         else
56.  
57.             ani[animationshoot.name].enabled = false;
58.  
59.  
60.  
61. }
62.  
63.  
64.