HFM Cluster Fails with Error: "An error occurred while adding the cluster to the list"

During Cluster/Server registration process, HFM uses the DCOM user to write the information into Windows  registry. If HFM DCOM user is unable to update registry the above error message will appear.

Check the HFM DCOM user has Write permission for the Windows registry key
HKEY_LOCAL_MACHINE\SOFTWARE\Hyperion Solutions\Hyperion Financial Management\Client