So, I've made this lower third design in AE using a lot of Knoll Light Factory lights. When I check the background is seemed to be transparent, checkboard appear, but when I render the TGA Sequence it shows black. I turned RGB+Alpha and the bit depth is 32 bit. Does anyone have any idea what the problem might be?
You probably used the Add blend mode or something like it. Blend modes do not create transparency. You need to get something like Knoll Unmult and apply it to the flare. You should then have transparency.
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA