Cannt get a function to run only on Client

Hey guys, I know there must be something that I'm doing wrong.

I'm tryng to call a function only on clients, but its also getting called on the server.

The message on the console appears to the server.

Help plss XD

 using UnityEngine;
 using System.Collections;
 using UnityEngine.Networking;
 
 public class CheckClient : NetworkBehaviour {
 
     void Update()
     {
         RunItOnlyOnClients ();
     }
 
     [ClientCallback]
     void RunItOnlyOnClients ()
     {
         print ("This should only appear to a Client");
     }
 }