how can I use, "MeshVertexColorList.SetColor Method (MeshFace, Color)" ?

Hi guys,

i tried, setColor Method with (MeshFace, Color)

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  private void RunScript(Mesh x, object y, ref object A)
  {

    Rhino.Geometry.Mesh mesh = new Rhino.Geometry.Mesh();

    mesh.Vertices.Add(0.0, 0.0, 1.0); //0
    mesh.Vertices.Add(1.0, 0.0, 1.0); //1
    mesh.Vertices.Add(2.0, 0.0, 1.0); //2
    mesh.Vertices.Add(3.0, 0.0, 0.0); //3
    mesh.Vertices.Add(0.0, 1.0, 1.0); //4
    mesh.Vertices.Add(1.0, 1.0, 2.0); //5
    mesh.Vertices.Add(2.0, 1.0, 1.0); //6
    mesh.Vertices.Add(3.0, 1.0, 0.0); //7
    mesh.Vertices.Add(0.0, 2.0, 1.0); //8
    mesh.Vertices.Add(1.0, 2.0, 1.0); //9
    mesh.Vertices.Add(2.0, 2.0, 1.0); //10
    mesh.Vertices.Add(3.0, 2.0, 1.0); //11

    mesh.Faces.AddFace(0, 1, 5, 4);
    mesh.Faces.AddFace(1, 2, 6, 5);
    mesh.Faces.AddFace(2, 3, 7, 6);
    mesh.Faces.AddFace(4, 5, 9, 8);
    mesh.Faces.AddFace(5, 6, 10, 9);
    mesh.Faces.AddFace(6, 7, 11, 10);

    mesh.Compact();

    mesh.VertexColors.SetColor(mesh.Faces[0], Color.Black);

    A = mesh;

  }

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but it seems, it doesn't work.

I can't see any change of color.

what did I wrong?

Thanks!