The "Help" may not be started because another application is using "Help" port. You may see this in the helpserver.log file, which is located in MagicDraw installation directory. If the server port is already in use, the java.rmi.server.ExportException appears in this file. To change Help port, you need to invoke the "Environment Options" dialog from the "Options" main menu. On the appeared dialog, "General" tab change the "Help Server Port", submit changes and try to invoke Help again.