Camera.RenderWithShader and Camera.SetReplacementShader

Hello!
I`m trying to implement a special effect when all objects in scene at once gain a "schematic" look. One can use RenderWithShader or SetReplacementShader to make camera render whole scene with a specific shader. However I have a problem with these methods.

If I use SetReplacementShader on my main camera, the scene becomes empty no matter what I pass as 'tag' parameter (null, "", "Geometry", "Opaque", etc):

Code (CSharp):

1.  
2.         if (enableSchematic)
3.         {
4.             MainCamera.SetReplacementShader(BlueprintCameraShader,null);
5.         }
6.         else
7.         {
8.             MainCamera.ResetReplacementShader();
9.         }
10.  

If I use RenderWithShader, nothing happens at all. I`ve read many articles so I found that there is some bug with this method and one must use two cameras:

Code (CSharp):

1.  
2.         if (enableSchematic)
3.         {
4.             MainCamera.gameObject.SetActive(false);
5.             BlueprintCamera.gameObject.SetActive(true);
6.             BlueprintCamera.RenderWithShader(BlueprintCameraShader, null);
7.         }
8.         else
9.         {
10.             BlueprintCamera.gameObject.SetActive(false);
11.             MainCamera.gameObject.SetActive(true);
12.             MainCamera.Render();
13.         }
14.  

Nothing happens with this implementation either.

All objects in the scene have either standard or legacy specular shaders. I`m trying to replace them with simple shader like this (taken from some Unity documentation):

Code (CSharp):

1.  
2. Shader "Simple colored lighting"
3. {
4.     // a single color property
5.     Properties{
6.         _Color("Main Color", Color) = (.5,.5,.5,1)
7.     }
8.         // define one subshader
9.     SubShader
10.     {
11.         Tags {"Queue" = "Geometry"}
12.         // a single pass in our subshader
13.         Pass
14.         {
15.             // use fixed function per-vertex lighting
16.             Material
17.             {
18.                 Diffuse[_Color]
19.             }
20.             Lighting On
21.         }
22.     }
23. }
24.  

Please help me