chown does not give me any right

I have a folder, my-folder. From its parent directory, I first do: sudo chown -cR mat: my-folder If I then do: chmod -cR 600 my-folder, I get: chmod: cannot access 'my-folder/build.sh': Permission denied chmod: cannot access 'my-folder/vmdk': Permission denied chmod: cannot access 'my-folder/.git': Permission denied chmod: cannot access 'my-folder/run.sh': Permission denied chmod: cannot access 'my-folder/docker': Permission denied chmod: cannot access 'my-folder/.gitignore': Permission denied Am I not supposed to fully own this folder and its content? Notes: Running sudo chmod -cR 600 my-folder does not print anything. mat is what I get when I type whoami.