Check the following to troubleshoot this issue: 1) If the agent is not installed on %ServerName;, run DpmAgentInstaller.exe ...

Check the following to troubleshoot this issue: 
1) If the agent is not installed on %ServerName;, run DpmAgentInstaller.exe with this DPM computer as a parameter. For details, see the DPM Deployment Guide.
2) To attach the computer correctly to this DPM server, run the SetDpmServer tool with the -Add option on the protected computer.
3) If the computer is protected by another DPM server, or if the protection agent has been uninstalled, remove the protected data sources on this computer from active protection. Then, remove the entry of this computer from the Agents tab in the Management task area.
4) If %ServerName; is a workgroup server, run SetDpmServer with the -UpdatePassword flag on the protected computer and Update-NonDomainServerInfo.ps1 on the DPM server to update the password.
5) If the DPM server and the protected computer are not in the same domain, ensure that there is a two-way trust setup between the two domains.