compositing using screen key issue

My question is this...
I am using adobe premier pro and when I load the cannon side stock footage from Detonation Films (who referred me to this forum and kick butt with their stock footage..nice plug lol) and apply the screen key to it it works but when I go to transform it to make it the right size and place for what I need, it turns the footage black again in the background of the effect. How do I fix this? I tried the luma key but it looks way too fake, and of course blue/greenscreen keying is not applicable since it is a black background in the stock footage.
-Terry