Playing 3d animation on hand trigger (joints)

Hi 

I am using the Hand joints template 

I have a 3d sphere that appears on the index finger when there is a pointing gesture. this sphere has an animation (spinning) , i tried on the "OnStart" event on the hand triggers (index finger) to add a behaviour that plays the animation. I added the animation mixer of my 3d prefab object but this doesnt work......i tried adding a PlayAnimation script but nothing happens either..the sphere is there but its not spinning...

Does anyone know how i can play an animation on the hand onStart trigger ?

Would really appreciate any advice :-) 

Thank You!!