Fusion Delta Keyer

Hey there, I'm trying to use delta keyer on a video of a phone with a green screen and blue screen background. I've only applied the delta keyer to the green screen yet, but when i try to insert a photo, it doesn't do anything, it's just blank. What am i doing wrong?

Post a screenshot of your node tree to show what you have connected where. If you can't post attachment because you are new to forum, you can use some free image hosting service.