Combine Basic Shadow Shader and Transparency Shader in Unity

I got some two shaders: One shader can receive shadows and another shader can display transparent material. When I try to combine them, the mesh is not displayed anymore and I'm not sure, where the error is exactly.

The shadow shader code:

 Shader "Custom/basicShadow" {
     Properties {
         _Color ("Main Color", Color) = (1,1,1,1)
         _MainTex ("Base (RGB)", 2D) = "white" {}
     }
     SubShader {
         Tags { "RenderType"="Opaque" }

         CGPROGRAM
         #pragma surface surf Lambert

         sampler2D _MainTex;
         fixed4 _Color;

         struct Input {
             float2 uv_MainTex;
             float4 color : COLOR;
         };

         void surf (Input IN, inout SurfaceOutput o) {
             fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
             o.Albedo = c.rgb;
             o.Albedo *= IN.color.rgb;
             o.Alpha = c.a;
         }
         ENDCG
     }
     Fallback "VertexLit"
 }

The transparency shader code:

  Shader "Custom/transparentShadow" {
       Properties {
            _MainTex ("Color (RGB) Alpha (A)", 2D) = "white" {}
            _Color ("Main Color", Color) = (1,1,1,1)
       }

       SubShader {
            Tags { "Queue"="Transparent" "RenderType"="Transparent" }
            LOD 200

            CGPROGRAM
            #pragma surface surf Lambert alpha
            #pragma target 3.0

            sampler2D _MainTex;
            fixed4 _Color;

            struct Input {
                 float2 uv_MainTex;
                 float4 color : COLOR;
            };

            void surf (Input IN, inout SurfaceOutput o) {
                 fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
                 o.Albedo = c.rgb;
                 o.Albedo *= IN.color.rgb;
                 o.Alpha = tex2D (_MainTex, IN.uv_MainTex).a *0.9;
            }

            ENDCG
       }
       Fallback "Diffuse"
  }

When adding the alpha tag to shadow tag, the mesh is not displayed anymore. Changing the tags of the shadow shader to Tags { "Queue"="Transparent" "RenderType"="Transparent" } however works, but doesn't result in a different outcome.