'rhel-7-server-optional-rpms' does not match a valid repository ID

Hello,

I am encountering this problem on a RedHat 7.3 server. I run the command as follows:
- subscription-manager repos --enable rhel-7-server-optional-rpms and it returns and error as follows:
- Error: 'rhel-7-server-optional-rpms' does not match a valid repository ID. Use "subscription-manager repos --list" to see valid repositories.

So here is output of subscription-manager repos --list
+----------------------------------------------------------+
Available Repositories in /etc/yum.repos.d/redhat.repo
+----------------------------------------------------------+
Repo ID: rhel-7-server-rpms
Repo Name: Red Hat Enterprise Linux 7 Server (RPMs)
Repo URL: https://rhs1v.xxx/pulp/repos/xxxxxx/Library/content/dist/rhel/server/7/7.4/$basearch/os
Enabled: 1

Repo ID: rhel-7-server-satellite-tools-6.2-rpms
Repo Name: Red Hat Satellite Tools 6.2 (for RHEL 7 Server) (RPMs)
Repo URL: https://rhs1v.xxx/pulp/repos/xxxxxx/Library/content/dist/rhel/server/7/7Server/$basearch/sat-tools/6.2/os
Enabled: 1

Repo ID: rhel-7-server-extras-rpms
Repo Name: Red Hat Enterprise Linux 7 Server - Extras (RPMs)
Repo URL: https://rhs1v.xxx/pulp/repos/xxxxxx/Library/content/dist/rhel/server/7/7Server/$basearch/extras/os
Enabled: 1

Repo ID: rhel-7-server-rhn-tools-rpms
Repo Name: RHN Tools for Red Hat Enterprise Linux 7 Server (RPMs)
Repo URL: https://rhs1v.xxx/pulp/repos/xxxxxx/Library/content/dist/rhel/server/7/7.4/$basearch/rhn-tools/os
Enabled: 0

Repo ID: rhel-server-rhscl-7-rpms
Repo Name: Red Hat Software Collections RPMs for Red Hat Enterprise Linux 7 Server
Repo URL: https://rhs1v.xxx/pulp/repos/xxxxxx/Library/content/dist/rhel/server/7/7.4/$basearch/rhscl/1/os
Enabled: 0

I have tried this on both my satellite server and the server where i want to enable the repository.

So how do I get it to match a valid Repository ID?

As always any help or guidance is greatly appreciated.

Regards,
Patrick