This error usually indicating that there is no entry of " gds_db 3050/tcp"
in the SERVICES file on either the client or the server machine. Add the entry to the file,
making sure there is a carriage return line feed after the entry if is is the last entry on
the list, and reconnect.  The location of the SERVICES file is usually in:

Unix  /etc/SERVICES
Windows  WINNT\system32\drivers\etc\SERVICES
  or
  WINDOWS\system32\drivers\etc\SERVICES
                or
                WINDOWS (Windows 98)