Master Repository Controller has to be binded with DM server. Once the connection was established, it will not accept rest of the DM Server.
Go to the DM Console -> Help -> White Paper
Fine the one named: WP_HPDM4.7 Repository Management. Troubleshooting steps: Connection Between the HPDM Server and the Master Repository Controller is the one you're looking for.
Since you're new to the DM, read the whole paper from begining might be a better choice.
