Ambient Occlusion in Vray


Hi, I’v been trying to render an Ambient Occlusion in Vray, by using the VrayExtraTex in the render element, as I saw in a tutorial.
But at the end of the render, I get this massage

I also tried to add some other passes in the “Rendering Elements”, but got the same error.
Does anybody know how to solve this?
Thanks a lot