EAM Agent not connecting to EAM Controller

I have an EAM Controller to which I want to assign a redundant pair of gateways as EAM Agents.

I am successful in adding gateway-A (master) as an EAM agent to the EAM controller. But it seems i cannot add the backup gateway-B as an EAM agent to the EAM Controller?

Is this a known issue or is there a workaround to fix this? thanks in advance.