DirectX 11 tessellation not working

Hi all, I am trying to have the most basic DirectX tessellation shader to work.

• My graphics card (nvidia geforce GTX 560 ti) supports DirectX 11

• I verified with dxdiag.exe that I have DirectX 11 installed

• I use Windows 7 and Unity 4.0.0b7 with DirectX 11 definitely activated both in Player Settings and in Preferences > General.

• I gave all the required textures correctly (diffuse, heightmap and normal map).

The following shader is an EXAMPLE coming from THIS LINK and it just doesn't work. I don't see any tessellation happening.

 Shader "Tessellation Sample" {
         Properties {
             _EdgeLength ("Edge length", Range(2,50)) = 15
             _MainTex ("Base (RGB)", 2D) = "white" {}
             _DispTex ("Disp Texture", 2D) = "gray" {}
             _NormalMap ("Normalmap", 2D) = "bump" {}
             _Displacement ("Displacement", Range(0, 1.0)) = 0.3
             _Color ("Color", color) = (1,1,1,0)
             _SpecColor ("Spec color", color) = (0.5,0.5,0.5,0.5)
         }
         SubShader {
             Tags { "RenderType"="Opaque" }
             LOD 300
 
             CGPROGRAM
             #pragma surface surf BlinnPhong addshadow fullforwardshadows vertex:disp tessellate:tessEdge nolightmap
             #pragma target 5.0
             #include "Tessellation.cginc"
 
             struct appdata {
                 float4 vertex : POSITION;
                 float4 tangent : TANGENT;
                 float3 normal : NORMAL;
                 float2 texcoord : TEXCOORD0;
             };
 
             float _EdgeLength;
 
             float4 tessEdge (appdata v0, appdata v1, appdata v2)
             {
                 return UnityEdgeLengthBasedTess (v0.vertex, v1.vertex, v2.vertex, _EdgeLength);
             }
 
             sampler2D _DispTex;
             float _Displacement;
 
             void disp (inout appdata v)
             {
                 float d = tex2Dlod(_DispTex, float4(v.texcoord.xy,0,0)).r * _Displacement;
                 v.vertex.xyz += v.normal * d;
             }
 
             struct Input {
                 float2 uv_MainTex;
             };
 
             sampler2D _MainTex;
             sampler2D _NormalMap;
             fixed4 _Color;
 
             void surf (Input IN, inout SurfaceOutput o) {
                 half4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
                 o.Albedo = c.rgb;
                 o.Specular = 0.2;
                 o.Gloss = 1.0;
                 o.Normal = UnpackNormal(tex2D(_NormalMap, IN.uv_MainTex));
             }
             ENDCG
         }
         FallBack "Diffuse"
     }

Console shows this warning:

 Shader warning in 'Custom/TessallationBasic': Program 'tessvert_surf', undeclared identifier 'UnityEdgeLengthBasedTess' (compiling for d3d11) at line 93

Thanks in advance for your attention.

Steak

Temporary post scriptum: At the moment the search server is totally down so I couldn't crawl around very much looking for a solution before asking. I don't see lot of information out there anyway on these topics. I might delete this post if I see it's a duplicate soon. (I like to be tidy)