Trying to get transparent DIFs

Hey guys.

Excuse me for being noob on this one - I'm only just starting with gfx coding and my knowledge is pretty small.

I'm trying to enable full translucency for DIFs. I'm using this pixel shader (no vert shader):

float4 main() : COLOR0
{
   float4 color;

   color[0] = 0.2;
   color[1] = 0.0;
   color[2] = 0.8;
   color[3] = 0.4;

   return color;
}

With these dbs:

new ShaderData( HomeBoyShader )
{
   DXVertexShaderFile 	= "shaders/homeBoyV.hlsl";
   DXPixelShaderFile 	= "shaders/homeBoyP.hlsl";
   pixVersion = 2.0;
};

new CustomMaterial( HomeBoy )
{
   mapTo = "Cyan";
   texture[0] = "scriptsAndAssets/data/interiors/CYAN";   // bumpmap texture in texture unit 0
 
   translucent = true;
   BlendOp = LerpAlpha;
   translucentBlendOp = LerpAlpha;
   translucentZWrite = true;
   attenuateBackFace = true;
 
   shader     = HomeBoyShader;
   version    = 2.0;
};

This works fine looking from one direction:


But not from the other:


I'm seriously new to this guys, so as much advice as possible would be helpful.

Cheers,
Ian