In order to check out and check in with Harweb you will need to install the SCM Agent software on your local machine. Links to the installation files for that should be present on the Harweb Home page. Can you try installing the agent to see if this resolves the problem? If it does not, please open a support case so that we can help to find the problem.
The installation media for SCM version 12.1 is no longer available because that version is no longer supported. Did you have plans to upgrade any time soon? Please open a support case for this as well if you have further questions.
Let me know if there is more I can do to help.
Thanks,
Melinda Skelton
CA Technologies Support Team