OnCollisionEnter only detects once

T$$anonymous$$s code works as it detects collision between a cube a floor and a Wall. The problem is the cube I drop (like t$$anonymous$$s video), is that I only detect the collsiion once with the wall and floor, even though the cube bounces around many times on the floor. Why is t$$anonymous$$s?

http://www.unity3dstudent.com/2010/07/beginner-b01-basic-collision-detection/

void OnCollisionEnter(Collision collision) {

     if (collision.gameObject.name=="Floor")
     {
         Debug.Log("Hit Floor");
     }
     if (collision.gameObject.name=="Wall")
     {
         Debug.Log("Hit wall");
     }
     
 }