Error:incorrect number of arguments to numeric-type constructor

Hey guys, Im following the book "Unity Shaders and Effects Cookbook" and im coming up with the following error. I took the source code from the book files and im getting this error which is either a misprint or something completely oblivious to me. So i checked the unity website and the code is the exact same. This is leaving me clueless. Can anyone tell me the problem.

 Shader "CookbookShaders/Chapter1/RampDiffuse" 
 {
     Properties 
     {
         _EmissiveColor ("Emissive Color", Color) = (1,1,1,1)
         _AmbientColor  ("Ambient Color", Color) = (1,1,1,1)
         _MySliderValue ("This is a Slider", Range(0,10)) = 2.5
         _RampTex ("Ramp Texture", 2D) = "white"{}
     }
     
     SubShader 
     {
         Tags { "RenderType"="Opaque" }
         LOD 200
         
         CGPROGRAM
         #pragma surface surf BasicDiffuse
 
         float4 _EmissiveColor;
         float4 _AmbientColor;
         float _MySliderValue;
         sampler2D _RampTex;
         
         inline float4 LightingBasicDiffuse (SurfaceOutput s, fixed3 lightDir, fixed atten)
         {
             float difLight = dot (s.Normal, lightDir);
             float hLambert = difLight * 0.5 + 0.5;
             float3 ramp = tex2D (_RampTex, float2(hLambert)).rgb; //This is //the line with the error
             
             float4 col;
             col.rgb = s.Albedo * _LightColor0.rgb * (ramp);
             col.a = s.Alpha;
             return col;
         }
 
         struct Input 
         {
             float2 uv_MainTex;
         };
 
         void surf (Input IN, inout SurfaceOutput o) 
         {
             float4 c;
             c =  pow((_EmissiveColor + _AmbientColor), _MySliderValue);
             
             o.Albedo = c.rgb;
             o.Alpha = c.a;
         }
         
         ENDCG
     } 
     
     FallBack "Diffuse"
 }