Problem with light's range

Hi,

I was attempting to create a simple subsurface scattering shader It's supose to only work with Point and Spot Lights But this happens: The light is behind the Quad

How do I link the lit area with the light's range?

Or at least how do I get the light's range? (So I can make a work around, the viewDir can be the meshe's normal, it's supose to be a 2D shader )

Heres the shader code:

 Shader "Custom/MyShader" {
     Properties { }
     SubShader {
         Pass {
             Tags { "LightMode" = "ForwardBase" }
             CGPROGRAM
             // ...
             ENDCG
         }
     
         Pass {
             Tags { "LightMode" = "ForwardAdd" }
     
             Blend One One
             ZWrite Off
     
             CGPROGRAM
     
             #pragma target 3.0
             #pragma multi_compile DIRECTIONAL POINT SPOT
             #pragma vertex vert
             #pragma fragment frag
     
             #include "UnityCG.cginc"
             #include "AutoLight.cginc"
             #include "UnityPBSLighting.cginc"
     
             struct VertexData {
                 float4 position : POSITION;
                 float2 uv : TEXCOORD0;
                 float3 normal : NORMAL;
             };
     
             struct Interpolators {
                 float4 position : SV_POSITION;
                 float2 uv : TEXCOORD0;
                 float3 normal : TEXCORD1;
                 float3 worldPos : TEXCOORD2;
             };
     
             Interpolators vert (VertexData v) {
                 Interpolators i;
                 i.position = UnityObjectToClipPos(v.position);
                 i.normal = UnityObjectToWorldNormal(v.normal);
                 i.uv = v.uv;
                 i.worldPos = mul(unity_ObjectToWorld, v.position);
                 return i;
             }
     
             float4 frag (Interpolators i) : SV_Target {
                 i.normal = normalize(i.normal);
                 float3 viewDir = normalize(_WorldSpaceCameraPos - i.worldPos);
 
                 float3 lightdir = normalize(_WorldSpaceLightPos0.xyz - i.worldPos);
 
                 float sss = saturate(dot(viewDir, -lightdir));
                 return float4(sss, sss, sss, 0);
             }
             ENDCG
         }
     }
 }