Fusion renderer doesn't show in viewer

Hello,
I am new in DaVinci and doing my first work in Fusion. I did lessons though. The scheme is pretty simple, I connected what I needed to Merge3d and then connected it to renderer3d to bring to Mediaout, in merge all is working, but in renderer I can see nothing and in editor my clip became just black. Where should I look for mistake?
Thank you

I found out the problem, it was silly) the image was behind the camera 3d, just a stupidity of a beginner