Vray single sided rendering problem


I made many simple tests and I simply cannot get it to work.
I want the backside of a plane to not render at all.
I have tried unchecking the double sided options of Vray Mtl and this dosent work.
I tried Having a double sided material, with one side being transparent (white refraction) this dosent work.

When doing scanline, with standard material, everything work fine. But as soon as I change to vray, it simply does not work.
I am at wits end!
Here is a really basic example.
The inside of teapot still hides the plane behind it.
The curved plane still shows on both sides (the top curved section).

Unticking still affect how the lighting affect the object, but it does not make it invisible in any way shape or form.

I need this because in my project, I have arches that overlap my scene. These arches have screens, and I dont want the screen to overlap and hide the rest of the interior, but I want them to be visible from the side of the column.