Making Vray Rect Lights transparent

[kosso_olli]

Hey guys,
one of our Maya people has a problem. In Max I can make a textured Vray Light easily transparent using the "Alpha from RGB intensity" option. That way the light becomes transparent where the map is black. You can see the effect in the attached pictures.
No here comes the question: How can this be achieved in Maya? I fiddled around with the Alpha is Lumincance option, but that doesn't work. Plugging a map into the alpha gain slot also didn't help.

Regards

Oliver

[Komposer]

here is the solution.

Because of the very unintuitiv formulation, I need´s years to find that trick!
Rect Tex A mean´s RT - Alpha.
You can map it or set it to black - means zero.
Cheers