Can't get submesh to work

I have been trying to make a mesh with multiple submeshes. But it just isn’t working. I am pretty sure I did what the documentation said me to do:

	void Start () {

        MeshFilter mf = gameObject.AddComponent<MeshFilter>();

        mf.mesh.vertices = new Vector3[]
            new Vector3(0,0,1f),
            new Vector3(1,0,1f),
            new Vector3(0,1,1f),
            new Vector3(1,1,1f),

        mf.mesh.subMeshCount = 2;
        mf.mesh.SetTriangles(new int[] { 0,1,2
                                        }, 0);
        mf.mesh.SetTriangles(new int[] { 2,1,3
                                        }, 1);

It only shows one of the triangles. Only one of the submeshs are visible at a time. Though I set submesh count to 2. Am I doing something wrong?

Doesn’t any one have a single clue about what I am doing wrong? :confused: