Had this issue today when pairing two VRMS servers sitting between different sites. To avoid this bug make sure you stay consistant with your SRM5 configuration when it comes to identifying servers. If you used the FQDN to identify the vCenter server for the initial SRM5 install but used the IP Address to reference the vCenter server in the VRMS configuration you will face this error on the pairing process. Regardless, SRM supports either IP Addresses or DNS names, either way stay consistant to avoid issues down the road
According to the VMWare forums this is an issue that was accidently excluded from the release notes and should be fixed in the future.