Hi,
I made this peppers video tutorial but it still renders the kitchen_probe.hdr image as a backdrop although I made the black box. I still get no black background!

For the black box I unchecked Self Shadow, Cast Shadow and Receive Shadow and checked Unseen by Rays in the Object properties dialog. But it still renders the backdrop image and I don't have a black background like in the video tutorial.
Please does anyone know what I'm doing wrong? TIA
Cheers,
Markus