OnCollisionEnter() dosen't work if one object dosen't move??

Maybe someone can explain me about the problem I encountered.
I have an object (arrow) that has a rigidbody, collider box and a script that contain OnCollisionEnter function and the other object (gate) only rigidbody and box collider. If both objects are moving, arrow feels the collision, otherwise not. I'm wrong somewhere or should I use another function?

Code (csharp):

1.    
2. public virtual void OnCollisionEnter(Collision collision)
3.     {          
4.         string _tag = collision.gameObject.tag;
5.         Debug.Log("hit: " + _tag);
6.         if(_tag == "Tower" || _tag == "Ammo")
7.             return;    
8.         Debug.Log("is alive");
9.         if(_tag == "Creep"  collision.gameObject.GetComponent<TDCreep>().isAlive)
10.         {
11.             collision.gameObject.GetComponent<TDCreep>().Hit(damage);
12.            
13.         }
14.         else
15.         {
16.             Debug.Log(collision.gameObject.name);
17.             Debug.Break();         
18.         }  
19.        
20.         poolAmmo.Add(this.transform);  
21.         poolEff.Add(Instantiate(explodeEff, collision.contacts[0].point, transform.rotation) as Transform, true);
22.         isVisible = false;
23.         isHitting = true;
24.     }

 

I found the problem. I had another object in the ray.