When drawing each gameobject, it seems that they ignore ambient / skybox color..

When i draw MeshRenderer with my custom pass, it's likely to ignore ambient & skybox color.
Two case below shows what i mean!

First case, using unity skybox and ambient color

Scene settings



Second case, skybox and ambient color disabled

Scene settings



Here is my custom pass

Code (CSharp):

1.  
2. public class LayeredRenderingPass : ScriptableRenderPass
3. {
4.     private LayerMask _layerMask;
5.     private LayerableTargetTable _table;
6.     private RenderingLayer[] _cache = new RenderingLayer[10000];
7.  
8.     private const string ShaderPassName_ForwardLit = "ForwardLit";
9.  
10.     public LayeredRenderingPass(RenderPassEvent renderPassEvent, LayerMask layerMask, LayerableTargetTable table)
11.     {
12.         this.renderPassEvent = renderPassEvent;
13.  
14.         _layerMask = layerMask;
15.         _table = table;
16.     }
17.  
18.     public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
19.     {
20.         CommandBuffer cmdBuffer = CommandBufferPool.Get("LayeredRenderingBuffer");
21.         context.ExecuteCommandBuffer(cmdBuffer);
22.         cmdBuffer.Clear();
23.  
24.         if (_table != null)
25.         {
26.             int count = _table.QueryNonAlloc(ref _cache, Filter);
27.             for (int i = 0; i < count; i++)
28.             {
29.                 RenderingLayer layer = _cache[i];
30.  
31.                 MeshRenderer renderer = layer.TargetRenderer;
32.                 MeshFilter meshFilter = renderer.GetComponent<MeshFilter>();
33.                 int subMeshCount = meshFilter.sharedMesh.subMeshCount;
34.                 int lastSubMeshIndex = renderer.subMeshStartIndex + subMeshCount;
35.  
36.                 for (int subMeshIndex = renderer.subMeshStartIndex; subMeshIndex < lastSubMeshIndex; subMeshIndex++)
37.                 {
38.                     Material mtr = renderer.sharedMaterials[subMeshIndex];
39.                     if (mtr != null)
40.                     {
41.                         int passIndex = mtr.FindPass(ShaderPassName_ForwardLit);
42.                         cmdBuffer.DrawRenderer(renderer, renderer.sharedMaterials[subMeshIndex], subMeshIndex, passIndex);
43.                     }
44.                 }
45.             }
46.         }
47.  
48.         context.ExecuteCommandBuffer(cmdBuffer);
49.         CommandBufferPool.Release(cmdBuffer);
50.     }
51.  
52.     private bool Filter(RenderingLayer renderingLayer)
53.     {
54.         return ((1 << renderingLayer.gameObject.layer) & _layerMask.value) != 0;
55.     }
56. }

I don't know how to render objects correctly....
Please help me