Can't View Alpha Channel (Cycles)

hi!

i’ve got a problem, and i was wondering if anyone might be able to help me out.

it used to be that, in the Compositor, you could attach a Viewer node to the Alpha output on a render layer, and get a black and white view of the image.

now, it seems, that this does not work - at least in Cycles anyway. when i do this now, i get a completely white screen with no alpha information. here’s a screen shot of what i’m talking about.


does anyone know why this might be happening? i’m sure it’s something i’m doing wrong.

thanks!

You didn’t render with a transparent background so no alpha. Enable the Transparent tickbox in Render / Film panel

derp! i knew it had to be my mistake! thank you very much Richard!