Try to add below technique  AlphaBlendEnable = true;

Code:
technique tech_00
{
	pass pass_00
	{
                AlphaBlendEnable = true; 
		VertexShader = null;
		PixelShader = compile ps_2_0 ColorToAlpha_PS();
	}
}

technique fallback { pass one { } }



Regards, Robert

Quote
Everything should be made as simple as possible, but not one bit simpler.
by Albert Einstein

PhysX Preview of Cloth, Fluid and Soft Body

A8.47.1P