Unet: [Command] not running

I have t$$anonymous$$s code:

 using UnityEngine;
 using UnityEngine.Networking;
 using System.Collections;
 
 public class ChatPlayer : NetworkBehaviour {
 
     // Use t$$anonymous$$s for initialization
     void Start () {
         
     }
     
     // Update is called once per frame
     void Update () {
         if (Input.GetKeyDown (KeyCode.Q))
             CmdHello ();
     }
 
     [Command]
     void CmdHello(){
         print ("Hello!");
     }
 }

T$$anonymous$$s script is in a player spawn prefab, and as you can see, if you press q, the client sends a command to print hello in its console. When I do press q, the server, nor client gets a message saying "Hello!".