Handling Explosions of PlayerSpawned Objects? "Trying to send command for object without authority."

So I want to spawn an explosion from a missile that the player shoots.

If I try to add the "explosion" like this:

(it is actually for a mine but it is actually the same)

Code (CSharp):

1.     void OnCollisionEnter(Collision coll)
2.     {
3.         Debug.Log("playercollision");
4.  
5.         if (coll.gameObject.tag == "Player")
6.         {
7.             CmdOnCollision();
8.             NetworkServer.Destroy(gameObject);
9.             col = true;
10.         }
11.  
12.      
13.     }
14.  
15.     [Command]
16.     void CmdOnCollision()
17.     {
18.  
19.         expo = (GameObject)Instantiate(
20.              exp,
21.             minecoll.transform.position,
22.             minecoll.transform.rotation);
23.  
24.  
25.         NetworkServer.Spawn(expo);
26.  
27.  
28.  
29.     }

it give me the following error

"Trying to send command for object without authority."

I actually have a workaround, where I check the collision of the missile with a static variable and then add the explosion prefab over the shooting script.
But there are 2 problems,

1st I can only instantiate one missile at once. If I instantiate more then one missile I only can destroy the last missile because the script loses the properties of the others.

2nd I want to have the bullets/missiles/mine etc. instantiate their explosions themselves and destroy themselves too.

How can I achieve giving my objects player authority?

 

got it fixed by myself

spawning with
NetworkServer.SpawnWithClientAuthority(expo, m_Identity);


getting the identity with

m_Identity = obj.GetComponent<NetworkIdentity>().connectionToClient;