* making sure that your listener is running (lsnrcrl stat)
ORA-12545: Connect failed because target host or object does not exist Cause: The address specified is not valid, or the program being connected to does not exist. Action: Ensure the ADDRESS parameters have been entered correctly; the most likely incorrect parameter is the node name. Ensure that the executable for the server exists (perhaps "oracle" is missing.) If the protocol is TCP/IP, edit the TNSNAMES.ORA file to change the host name to a numeric IP address and try again.