You also have to have the server parameters configured in the TNSNAMES.ORA file for each client. For me, this file is in the C:\Oracle\Ora81\NETWORK\ADMIN folder. You can configure this using Net8 Easy Config utility in your Oracle program group. Once you have the configuration correct, you can just copy the TNSNAMES.ORA file to each client pc.
Mark McCasland
Midlothian, TX USA