Are you sure that the other node has connected to the cluster? Does it appear in the locator log?
If you're sure it is connected, can you also connect to the locator with gfsh and do 'list members' to see if what's displayed there is consistent with what pulse is showing.
You may also want to check that name resolution works everywhere - does every system know how to resolve all IPs of all other systems?
What version of JDK are you using and what OS are all these components running on?
--Jens