Shader Darkening the UI sprite behind it!

My shader is a 2d refraction shader applied to a sphere particle object, but for some reason it makes the sprite from the UI dark behind it. I want my shader to ignore all lighting or just be completely transparent and only magnify whats behind it. Please help!

here is an img of the issue, notice how the circles are dark. i want them completely transparent http://imgur.com/bmrqA9s

 Shader "MyShaders/UnlitTest" {
     Properties {
  _Color ("Main Color", Color) = (1,1,1,1)
         _SpecColor ("Specular Color", Color) = (0.5, 0.5, 0.5, 1)
         _Shininess ("Shininess", Range (0.03, 1)) = 0.3
         _MainTex ("Base (RGB)", 2D) = "white" {}
         _BumpMap ("Normalmap", 2D) = "bump" {}
         _DistAmt  ("Distortion", range (0,128)) = 10
     }
     SubShader {
         GrabPass { }
        
 Tags {"RenderType"="Transparent" "Queue"="Transparent" "IgnoreProjector"="True" "ForceNoShadowCasting"="True"  }
         LOD 200
        
         CGPROGRAM
         #pragma exclude_renderers gles
         #pragma vertex vert
         #pragma surface surf BlinnPhong alpha
         #include "UnityCG.cginc"
  
         float4 _Color;
         float _Shininess;
         sampler2D _MainTex;
         sampler2D _BumpMap;
         sampler2D _GrabTexture;
         float _DistAmt;
         float4 _GrabTexture_TexelSize;
  
         struct Input {
             float2 uv_MainTex;
             float2 uv_BumpMap;
             float4 proj : TEXCOORD;
         };
        
         void vert (inout appdata_full v, out Input o) {
             UNITY_INITIALIZE_OUTPUT(Input,o)
               float4 oPos = mul(UNITY_MATRIX_MVP, v.vertex);
               #if UNITY_UV_STARTS_AT_TOP
                   float scale = -1.0;
               #else
                   float scale = 1.0;
               #endif
             o.proj.xy = (float2(oPos.x, oPos.y*scale) + oPos.w) * 0.5;
             o.proj.zw = oPos.zw;
         }
 
         void surf (Input IN, inout SurfaceOutput o) {
             half3 nor = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
            
             float2 offset = nor * _DistAmt * _GrabTexture_TexelSize.xy;
             IN.proj.xy = offset * IN.proj.z + IN.proj.xy;
             half4 col = tex2Dproj( _GrabTexture, UNITY_PROJ_COORD(IN.proj));
            
             half4 tex = tex2D(_MainTex, IN.uv_MainTex);
             o.Albedo = tex.rgb * _Color.rgb * col.rgb;
             o.Normal = nor.rgb;
             o.Specular = _Shininess;
             o.Gloss = col.a;
             o.Alpha = col.a;
         }
       
         
         ENDCG
     }
     FallBack "Diffuse"
 }