InstantiatePrefab parenting dosen't work

Hi, iam using this code. But it dosent parent the instantiated prefab.

public static void InstantiatePrefab(string path, string name, string parentName)
{
    if (!CheckIfObjectAlreadyExists(name, parentName))
    {
        GameObject obj = Resources.Load<GameObject>(path + "/" + name);
        GameObject result = UnityEditor.PrefabUtility.InstantiatePrefab(obj as GameObject) as GameObject;

        result.transform.SetParent(GetParentObject(parentName).transform);


    }
}

What is wrong with this method?

It works as long as the prefab was once in the scene. If the scene was saved with the instantiated prefab in it… Dirty workaround …