Custom Terrain AddPass not working

I've read a gamasutra article (http://www.gamasutra.com/blogs/AndreyMishkinis/20130716/196339/Advanced_Terrain_Texture_Splatting.php), read about creating shaders in unity's documents, read about creating custom terrain shaders (https://alastaira.wordpress.com/2013/12/07/custom-unity-terrain-material-shaders/)... Then after making some shaders I've tried to make my own terrain shader for unity, a texture blending shader (not only splat mapping), and I've come up with a working (not perfect) shader. The problem is, the addpass shader isn't working. It's falling back to the "fallback" shader and even if I take the fallback line off, it still doesn't work, just shows like I'm painting the 4th texture in the terrain.

If anyone can help me find out what is wrong I would be really grateful. Anyone can use the shader if you like it.

The shader is here (did not apply the normals yet, trying to fix the base texture before) :

 Shader "Hidden/Raed Wulf/Terrain/BlendTexture-AddPass" {
     Properties{
         //control splat map
         [HideInInspector] _Control("Control (RGBA)", 2D) = "red" {}
 
         //textures Alpha is height
         [HideInInspector] _Splat3("Layer 3 (A)", 2D) = "white" {}
         [HideInInspector] _Splat2("Layer 2 (B)", 2D) = "white" {}
         [HideInInspector] _Splat1("Layer 1 (G)", 2D) = "white" {}
         [HideInInspector] _Splat0("Layer 0 (R)", 2D) = "white" {}
 
         //normal maps
         [HideInInspector] _Normal3("Normal 3 (A)", 2D) = "bump" {}
         [HideInInspector] _Normal2("Normal 2 (B)", 2D) = "bump" {}
         [HideInInspector] _Normal1("Normal 1 (G)", 2D) = "bump" {}
         [HideInInspector] _Normal0("Normal 0 (R)", 2D) = "bump" {}
 
         // used in fallback on old cards & base map
         [HideInInspector] _MainTex("BaseMap (RGB)", 2D) = "white" {}
         [HideInInspector] _Color("Main Color", Color) = (1,1,1,1)
         
     }
 
     SubShader{
         Tags{
             "SplatCount" = "4"
             "Queue" = "Geometry-99"
             "IgnoreProjector" = "True"
             "RenderType" = "Opaque"
         }
 
         CGPROGRAM
         #pragma surface surf Standard exclude_path:forward decal:add
         #pragma multi_compile_fog
         #pragma target 3.0
         // needs more than 8 texcoords
         #pragma exclude_renderers gles
         #include "UnityPBSLighting.cginc"
         
         // Access the Shaderlab properties
         uniform sampler2D _Control;
         uniform sampler2D _Splat0,_Splat1,_Splat2,_Splat3;
 
         // Surface shader input structure
         struct Input {
             float2 uv_Control : TEXCOORD0;
             float2 uv_Splat0 : TEXCOORD1;
             float2 uv_Splat1 : TEXCOORD2;
             float2 uv_Splat2 : TEXCOORD3;
             float2 uv_Splat3 : TEXCOORD4;
         };
 
         float4 blend(float4 texA, float aA, float4 texB, float aB)
         {
 
             float depth = 0.1;
             float ma = max(texA.a + aA, texB.a + aB) - depth;
 
             float b1 = max(texA.a + aA - ma, 0.0);
             float b2 = max(texB.a + aB - ma, 0.0);
 
             return (texA * b1 + texB * b2) / (b1 + b2);
 
         }
 
             
         // Surface Shader function
         void surf(Input IN, inout SurfaceOutputStandard o) {
             fixed4 tex0 = tex2D(_Splat0, IN.uv_Splat0);
             fixed4 tex1 = tex2D(_Splat1, IN.uv_Splat1);
             fixed4 tex2 = tex2D(_Splat2, IN.uv_Splat2);
             fixed4 tex3 = tex2D(_Splat3, IN.uv_Splat3);
 
             fixed4 splat_control = tex2D(_Control, IN.uv_Control);
             fixed4 col;
 
             col = blend(tex0, splat_control.r, tex1, splat_control.g);
             col = blend(col, splat_control.r + splat_control.g, tex2, splat_control.b);
             col = blend(col, splat_control.r + splat_control.g + splat_control.b, tex3, splat_control.a);
 
             o.Albedo = col.rgb;
             o.Alpha = 0.0;
                         
         }
         ENDCG
     }
 
         Fallback "Hidden/TerrainEngine/Splatmap/Diffuse-AddPass"
         //Fallback off
 }