In my experience, this generally has to do with connectivity between the client (PC) and the PPM server. The workbench connects to the RMI port that's defined in server.conf, usually 1099. If there are firewalls in place, you may need to check to make sure that port is open between your PC and the server. Also, the hostname that is defined in the server.conf parameter RMI_URL must be one that is accessible from your PC. Again, this is generally a networking issue for the connectivity between the client and the server.