I'll take a wild guess and say that you just started using the Rotobrush tool once you found it, and that you didn't look at any of the Rotobrush training material.
How close is that to the truth?
Why are you adding a green background? If you are going to key out the green later you are wasting your time.
Without a a screenshot of the whole app with the modified properties of the layers that are giving you problems revealed it's nearly impossible for us to figure out what is going on, Select the layers, press the U key twice and print screen and paste to the reply field on this forum or Shift + Cmnd/Ctrl + 3 on a Mac then drag it from the desktop. Maybe we can help you find the user error in your project.
The only guess I have is that you don't know how to use Rotobrush.
I have to concur with Dave - it might be a good idea to actualyl read the help and watch some basic tutorials. You don't know what you are doing.
Well yes, that is kinda how it went. Saw a video of someone using the roto brush while looking for something to key away the background and did what they did in the video. Except when I render it I get errors and what you see in the picture.
Well, thats a really good question why I'm adding a green solid. I could have placed the image I wanted to use immediantly behind them. And ineed this is the first time I'm using the roto brush. Don't know if it's this you want to see. A lot of strokes changes.
Sorry, but I'm new to after effects so I hope you can stay patient with me while trying to help me. Premiere pro is my cup of tea.
Really aprriciate you all replied and want to help me.
I solved it. The render tripped because I cut out the space from the arms.