Problem in reloading animation at interval time

I have an animated prefab .

At the start of scene this prefab start an animation.... I want that after 20 seconds its animation returns at initial state and play again.

I have tried to invoke this code

 function myObjAnimation(){
     myobj.GetComponent.<Animation>().Play();
     myobj.GetComponent.<Animation>().Rewind();
 }

with

  InvokeRepeating("myObjAnimation",20, 20);

in Update()

but only the first animation it's executed, on next invocation the animation is rewinded but remains freezed at initial state.