Shadermaterial not showing - only on other gameobjects

I tried the VR Sample Scene with the LWR - pipline.
I have added a script where I add a mesh, but it is only showing on the other materials but not on the "ground" or in the "air"

As we are all new to the LWR.. I hope someone can help me here

ONLY the color behind objects is showing !

this is it.. how it looks...



you can see, the navmesh border I added via script.. bu it tis only displayed when there are other gameobjects in front.

what do I have to change to make it show up ?

this is the shader


this is the code of the script which is from github user: FlaFla2

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. /// \brief A generic component that renders a border using the given polylines.  The borders are double sided and are oriented
5. ///        upwards (ie normals are parallel to the XZ plane)
6. [AddComponentMenu("Vive Teleporter/Border Renderer")]
7. [ExecuteInEditMode]
8. public class BorderRenderer : MonoBehaviour {
9.     private Mesh[] CachedMeshes;
10.     /// Material used to render the border mesh.  Note: UVs are set up so that v=0->bottom and v=1->top of border
11.     [Tooltip("Material used to render the border mesh.  UV's are set up so that v=0->bottom and v=1->top.  u is stretched along each edge.")]
12.     public Material BorderMaterial;
13.  
14.     [System.NonSerialized]
15.     public Matrix4x4 Transpose = Matrix4x4.identity;
16.  
17.     [SerializeField] [Range(0,1)]
18.     [Tooltip("Alpha (transparency) of the border mesh.")]
19.     public float BorderAlpha = 1.0f;
20.     private float LastBorderAlpha = 1.0f;
21.  
22.     [Tooltip("Layer to render the mesh at.")]
23.     private int AlphaShaderID = -1;
24.  
25.     /// Polylines that will be drawn.
26.     public BorderPointSet[] Points {
27.         get
28.         {
29.             return _Points;
30.         }
31.         set
32.         {
33.             _Points = value;
34.             RegenerateMesh();
35.         }
36.     }
37.     private BorderPointSet[] _Points;
38.  
39.     public float BorderHeight
40.     {
41.         get
42.         {
43.             return _BorderHeight;
44.         }
45.         set
46.         {
47.             _BorderHeight = value;
48.             RegenerateMesh();
49.         }
50.     }
51.     [SerializeField]
52.     [Tooltip("Height of the border mesh, in meters.")]
53.     private float _BorderHeight = 0.2f;
54.  
55.     void Update()
56.     {
57.         if (CachedMeshes == null || BorderMaterial == null)
58.             return;
59.  
60.         if (LastBorderAlpha != BorderAlpha && BorderMaterial != null)
61.         {
62.             BorderMaterial.SetFloat("_Alpha", BorderAlpha);
63.             LastBorderAlpha = BorderAlpha;
64.         }
65.  
66.         foreach (Mesh m in CachedMeshes)
67.             Graphics.DrawMesh(m, Transpose, BorderMaterial, gameObject.layer, null, 0, null, false, false);
68.     }
69.  
70.     void OnValidate()
71.     {
72.         RegenerateMesh();
73.  
74.         if (AlphaShaderID == -1)
75.             AlphaShaderID = Shader.PropertyToID("_Alpha");
76.         if(BorderMaterial != null)
77.             BorderMaterial.SetFloat(AlphaShaderID, BorderAlpha);
78.     }
79.  
80.     public void RegenerateMesh()
81.     {
82.         if (Points == null)
83.         {
84.             CachedMeshes = new Mesh[0];
85.             return;
86.         }
87.         CachedMeshes = new Mesh[Points.Length];
88.         for (int x = 0; x < CachedMeshes.Length; x++)
89.         {
90.             if (Points[x] == null || Points[x].Points == null)
91.                 CachedMeshes[x] = new Mesh();
92.             else
93.                 CachedMeshes[x] = GenerateMeshForPoints(Points[x].Points);
94.         }
95.     }
96.  
97.     private Mesh GenerateMeshForPoints(Vector3[] Points)
98.     {
99.         if (Points.Length <= 1)
100.             return new Mesh();
101.  
102.         Vector3[] verts = new Vector3[Points.Length * 2];
103.         Vector2[] uv = new Vector2[Points.Length * 2];
104.         for(int x=0;x<Points.Length;x++)
105.         {
106.             verts[2 * x] = Points[x];
107.             verts[2 * x + 1] = Points[x] + Vector3.up * BorderHeight;
108.  
109.             uv[2 * x] = new Vector2(x % 2, 0);
110.             uv[2 * x + 1] = new Vector2(x % 2, 1);
111.         }
112.  
113.         int[] indices = new int[2 * 3 * (verts.Length - 2)];
114.         for(int x=0;x<verts.Length/2-1;x++)
115.         {
116.             int p1 = 2*x;
117.             int p2 = 2*x + 1;
118.             int p3 = 2*x + 2;
119.             int p4 = 2*x + 3;
120.  
121.             indices[12 * x] = p1;
122.             indices[12 * x + 1] = p2;
123.             indices[12 * x + 2] = p3;
124.             indices[12 * x + 3] = p3;
125.             indices[12 * x + 4] = p2;
126.             indices[12 * x + 5] = p4;
127.  
128.             indices[12 * x + 6] = p3;
129.             indices[12 * x + 7] = p2;
130.             indices[12 * x + 8] = p1;
131.             indices[12 * x + 9] = p4;
132.             indices[12 * x + 10] = p2;
133.             indices[12 * x + 11] = p3;
134.         }
135.  
136.         Mesh m = new Mesh();
137.         m.vertices = verts;
138.         m.uv = uv;
139.         m.triangles = indices;
140.         m.RecalculateBounds();
141.         m.RecalculateNormals();
142.         return m;
143.     }
144. }