Have you checked your Discover, Discover_Inst, Discover_DB enabled at the Server. Set your Db2COMM variable to TCPIP, check your port number in the services file.
Now in the WINDOWS machine Catalog the Server Node with proper IP Address and Server Machine Name.
check the "CATALOG TCPIP ..." command.
Now you catalog your database at that node.
You shouldnot face this problem again.