Cannot find rails package

I have the following channels:

$ nix-channel --list            
home-manager https://github.com/nix-community/home-manager/archive/release-22.11.tar.gz
unstable https://nixos.org/channels/nixos-unstable

On search.nixos.org I can see the rubyPackages_3_2.rails but I cannot find in the local system. I am using a Mac on Intel. This command can find the package:
nix-env -f “” -qaP | grep rails

What command are you using to install it, and what is the exact error?