Help Addition of Obi Collider

[Richard]

Hello.

This is very basic question, but I cannot add Obi collider by AddComponent.
My code is.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ManSetting : MonoBehaviour
{
    public GameObject man;
    // Start is called before the first frame update
    void Start()
    {
        man.AddComponent<MeshCollider>();
        man.AddComponent<ObiCollider>();
    }
}

However, error massage is displayed like the image.