External Root CA not showing up in Trusted Root Certification Authorities

I have made a self signed root CA, which I want to distribute to all
the clients in my domain, so they can login on the intranet, without
an SSL error message saying the root CA is nog trusted. I followed the
instructions on the Microsoft page:

1. I edited the Default Domain Policy and added the self signed root
CA using the Import function at the location: Windows Settings -->
Security Settings -->Public Key Policies --> Trusted Root
Certification Authorities.
2. I rebooted the client and the server

Unfortunately the self signed root CA does not show up on the clients
in the domain. Am I missing something?

Thanks for your help,

Mac Leus