Add LOD models to LODGroup programmatically

Hello, i am trying to add 4 LOD levels (models) to LODGroup contained in Resources folder programmatically. I have followed the example from http://docs.unity3d.com/ScriptReference/LODGroup.SetLODS.html but it did not work exactly as i would expect. When i run the code i didn't see any change between the LODs during the movement of camera from far to near and also in my Game mode in Statistics window under Tris it was showing the sum of triangles from all my LOD models during the camera movement instead of displaying the correct number of triangles in each LOD change (while the triangles number was correct in case of using the Inspector).

Here is my code:

Vector3 obj_position = new Vector3 (-3.5f, -0.257643f, -5.0f);

LODGroup group_comp;

 void Start () {

     group_comp = (LODGroup)gameObject.AddComponent (typeof(LODGroup));
     var lods = new LOD[4];
     var primType = (GameObject) Resources.Load ("dragon_vrip", typeof(GameObject)); 

     for (int i=0; i<4; i++) {
         
         switch(i){
             
         case 0: primType = (GameObject) Resources.Load ("dragon_vrip", typeof(GameObject));        //LOD 0
             break;
             
         case 1: primType = (GameObject) Resources.Load ("dragon_vrip_res2", typeof(GameObject));    //LOD 1
             break;
             
         case 2: primType = (GameObject) Resources.Load ("dragon_vrip_res3", typeof(GameObject));   //LOD 2
             break;
             
         case 3: primType = (GameObject) Resources.Load ("dragon_vrip_res4", typeof(GameObject));   //LOD 3
             
             break;
         }

         var go = (GameObject)Instantiate(primType, obj_position, Quaternion.identity ); 
         
         go.transform.parent = gameObject.transform;
         go.transform.localScale = new Vector3 (1, 1, 1);

         var renderers = new Renderer[1];
         renderers[0] = go.renderer;
         lods[i] = new LOD (1.0F / (i+4), renderers);
         
     }

     group_comp.SetLODS (lods);
     group_comp.RecalculateBounds();

any help would be appreciated

Thanks in Advance.