I am not able to attach the outAlpha or outTransparency of a file texture to the opacity map of a vray material. I select outAlpha and then the RGB of the opacity map and the connection doesn’t take. MMB Dragging the file right onto the attribute editor connects the outColor, even if there is an alpha in the texture. I have tried tga and tiff.
I can reproduce this problem even with 1.5 sp1.
I’ll see if it can be fixed.
As a workaround you can use the connection editor, by clicking other in the menu.