Colliders doesn t collide with CharacterController

Hi, i have a character controller and a cube in my scene what i am trying to do is playing animation that was attached on the cube when the player collide with it

this is my script

function OnCollisionEnter(hit:Collision){
  if(hit.gameObject,tag=="Player")
   animation.Play("rotate");
}
this script is attached to the cube but when it collide nothing happen may someone tell me what's wrong?? thanks

Check the bottom of the BoxCollider documentation page for the rules for collisions and triggers and see if you have satisfied the requirements to get that event.