I use deploy key on my repos without any problem... now i want to create deploy key for a repo that belongs to an organization (that I'm a member of), i did it the usual way:

• generate new ssh key:
  ssh-keygen -t ed25519 -C "test@example.com"
• adding SSH key to the ssh-agent
  ssh-add ~/.ssh/key_file
• add (public key) to the repo deploy keys (github).

but when I try to clone the repo:
git clone git@github.com:org_name/repo_name.git
I get this error message:
"ERROR: Repository not found.
fatal: Could not read from remote repository."
I tried changing the key multiple times without luck.
not sure what is happening, any help will be appreciated.