Additive Blending Shader for Mobile - parse error

Hello!

I'm working on custom surface shader, which blending two textures into one additive image with transparency (alpha channel).
I have very low knowledge about shaders and I mostly improvise.
Generally I've done it by mixing some parts of Unity built-in shaders. And here comes the problem:

1. When I'm using only CGPROGAM instructions without Pass, shader works in editor and it effects are visible in Game viewport, even in runtime. BUT, if I hit Play button on other scene, then switch it (in-game) to that with shader - shader aren't working anymore. Object is invisible.

2. When I'm using CGPROGRAM instructions with Pass and SetTexture functions (CG instructions are outside Pass brackets) then it works. Unfortunately, in that case I lost blending, so this isn't what I want.

3. When I'm put CGPROGRAM instructions into Pass brackets I receive error: Parse error: syntax error, unexpected TOK_PASS, expecting TOK_SETTEXTURE or '}' at line 38

I don't know what I'm doing wrong.
Below is my code.
Unity version: 2017.1.0f3
Target platform: Android

 Shader "Custom/AdditiveTransparentBlending"
 {
     Properties
     {
         _MainTex("Texture 1", 2D) = "white" {}
         _Texture2("Texture 2", 2D) = "white" {}
         _Blend("Blend", Range(0, 1)) = 0.5
     }
     
     SubShader
     {
         Pass
         {
             Tags
             {
                 "Queue" = "Transparent"
                 "IgnoreProjector" = "True"
                 "RenderType" = "Transparent"
             }
             Blend SrcAlpha One
             Cull Off
             Lighting Off
             ZWrite Off
             Fog{ Color(0,0,0,0) }
 
             BindChannels
             {
                 Bind "Color", color
                 Bind "Vertex", vertex
                 Bind "TexCoord", texcoord
             }
 
             CGPROGRAM
             #pragma target 2.0
             #include "UnityCG.cginc"
             //#pragma exclude_renderers flash
             #pragma surface surf Lambert vertex:vert noforwardadd keepalpha
 
             struct Input
             {
                 float2 uv_MainTex;
                 float2 uv_Texture2;
                 float4 color : Color;
             };
 
             float _Blend;
             sampler2D _MainTex;
             sampler2D _Texture2;
 
             void vert(inout appdata_full v, out Input o)
             {
                 UNITY_INITIALIZE_OUTPUT(Input,o);
                 o.color = v.color;
             }
 
             void surf(Input IN, inout SurfaceOutput o)
             {
                 fixed4 c = tex2D(_MainTex, IN.uv_MainTex);
                 fixed4 c2 = tex2D(_Texture2, IN.uv_Texture2);
 
                 o.Albedo = (c.rgb * IN.color.rgb) * _Blend + (c2.rgb * IN.color.rgb) * (1 - _Blend);
                 o.Alpha = (c.a * IN.color.a) * _Blend + (c2.a * IN.color.a) * (1 - _Blend);
 
                 o.Albedo *= 2;
             }
 
             ENDCG
             /*
             Pass
             {
                 SetTexture[_MainTex]
                 SetTexture[_Texture2]
                 {
                     //combine texture * primary
                     ConstantColor(0,0,0,[_Blend])
                     Combine texture Lerp(constant) previous
                 }
             }*/
         }
     }
     //Fallback "Diffuse"
 }