"Follow Target" script with a prefab (C#) Help me please!

I want to follow target a prefab but I don’t arrive to do that.
The script:

using System;
using UnityEngine;

namespace UnityStandardAssets.Utility
{
public class FollowTarget : MonoBehaviour
{
public Transform target;
public Vector3 offset = new Vector3(0f, 7.5f, 0f);

    private void LateUpdate()
    {
        transform.position = target.position + offset;
    }
}

}

You can use unity’s built in Navigation if your prefab is on the ground. Navigation in the Manual