How do I use RPC ,sync player health bar in unity3d c#

I have a network script . The health bar shows on top of the players head. But thing the health bar is not updating when I shoot. In other word its not taking damage when I shoot. I must be forgetting something . Here is my code :
using UnityEngine;
#if ENABLE_MULTIPLAYER
using UnityEngine.Networking;
using UnityEngine.UI;
if ENABLE_MULTIPLAYER
public class Health : NetworkBehaviour
#else
public class Health : MonoBehaviour
#endif
{

int health;
Healthbar healthbar;

    void Start()
    {
        
      		healthbar = FindObjectOfType<Healthbar>();
        if (healthbar == null) 
        {
		Debug.LogError("Healthbar class is not found in scene!");
	}
    
    }

#if ENABLE_MULTIPLAYER
if (isServer) {
RpcDamage(amount, position, force, radius, attacker);
}
// Execute the method on the local instance. Use isClient instead of isServer because the client and server may be the same instance
// in which case the method will be called with the Rpc call.
if (!isClient) {
#endif
DamageLocal(amount, position, force, radius, at
[ClientRpc]
private void RpcDamage(float amount, Vector3 position, Vector3 force, float radius, GameObject attacker)
{
DamageLocal(amount, position, force, radius, attacker);
}

}

}

good article about your case: http://unity3d.com/learn/tutorials/topics/multiplayer-networking/networking-player-health?playlist=29690