Load Scene when websocket receive message

I am using websocket-sharp, and it can connect to my websocket server and can receive message. I try to load scene from onMessage, but it doens't work. Following is onMessage:

    ws.OnMessage += (sender, e) =>
    {
        Debug.Log("before load scene");
        SceneManager.LoadScene("Game");
        Debug.Log("after load scene");
    };

It will print before load scene, but it can not load scene and it doesn't print after load scene

Try creating a new class called SceneListener which is a MonoBehaviour. Do the following:

private bool _shouldSwitch;
void Start() {
    _shouldSwitch = false;
    DontDestroyOnLoad(this.gameObject);
}

void Update() {
    if (_shouldSwitch) {
        _shouldSwitch = false;
        Debug.Log("before load scene");
        SceneManager.LoadScene("Game");
        Debug.Log("after load scene");
    }
}

public void Switch() {
    _shouldSwitch = true;
}

Then pass a reference from the instance of SceneListener to your callback:

ws.OnMessage += (sender, e) =>
{
    sceneListener.Switch()
};