2Sided Shader - Unity+ASE

Hi all,

I’m a noob doing shaders and VFX, but for now it’s something I like so much. I’m creating some VFX on Playstark in Barcelona and now I need an Helix using scroll and 2 sided shader.
The problem is on the configuration, I search for documentation but I don’t understand what I’m doing wrong. The front face alpha is cutting the backface and this one is painting over the opaque part of the frontface.

What am I doing wrong? I attach images to show the issue.