Shader issue after upgrade to 4.5.2

Hi,

After we upgraded our project from Unity 4.2.2 to 4.5.2, some of the shaders became darker than before on Android.

We attached 2 screenshots and the shader source (see line 59) to provide as much information as possible. Both screens are running on a Kindle Fire.

Any hints??? Thanks!

 Shader "Custom/Lit/Tiles" {
    
   Properties {
     _Color ("Main Color", Color) = (1,1,1,1)
     _MainTex ("Base (RGB)", 2D) = "white" {}
   }
  
   Category {
   
     Tags { "RenderType"="Opaque" "IgnoreProjector"="True" "Queue"="Geometry" }
       
     SubShader {
     
       LOD 200
      
       Pass {
          
         CGPROGRAM
            
           #pragma vertex vert
           #pragma fragment frag
           #pragma fragmentoption ARB_precision_hint_fastest
           
           #include "UnityCG.cginc"
           
           struct appdata {
             float4 vertex : POSITION;
             float3 normal : NORMAL;
             float2 texcoord : TEXCOORD0;
           };
          
           struct v2f {
             float4 pos : SV_POSITION;
             float2 uv : TEXCOORD0;
             float3 colorMul : COLOR0;
           };
          
           uniform sampler2D _MainTex;
           uniform float4 _MainTex_ST;
           uniform float4 _Color;
           uniform float4 _RimColor;
          
           v2f vert (appdata_base v) {
           
             v2f o;
             o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
            
             o.colorMul.rgb = ShadeVertexLights(v.vertex, v.normal) * _Color;
            
             o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
            
             return o;
           }
          
           float4 frag(v2f i) : COLOR {
           
             float4 texcol = tex2D(_MainTex, i.uv);
             
             texcol.rgb *= i.colorMul * 2.0; //@BUG@ Not working on Unity 4.5.2 for Android!
             
             return texcol;
           }
          
         ENDCG
       }
     }
   }
 }