how to get transform working on null object from imported model?

Hi, I imported an object using Cinema4D. The object is one "empty null" object containing several other empty object that hold regular objects. Now I’m trying to anymate that top most empty object with C# but that just does nothing. I tried:

 transform.Rotate (Time.deltaTime * 2, Time.deltaTime * 2, Time.deltaTime * 2);

I also tried other transform methods like

 transform.eulerAngles

or

 transform.rotation

also

 transform.position

none of these work. HOWEVER, when doing this manually: literally clicking the object, then clicking on the "rotation X" value and changing the value manually by tiping in another value, it does work. Why can’t I access it in code?

Here is my code:

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

 public class move : MonoBehaviour {
 // Update is called once per frame
 void Update () {
     print (transform.rotation);
     transform.Rotate (Time.deltaTime * 2, Time.deltaTime * 2, Time.deltaTime * 2);
 }
 }

do you have any ideas what could be the isse? Thank you.