Hi , We have a server running Oracle 7.3.3 (i know very old!!) and we got to
connect to Oracle 9i database which is remote to this server.
I have made the entry in tnsnames.ora file and could successfully run
tnsping. But when I try to connect to it by sqlplus , it gives an error

But when we try to connect to another server which is running Oracle, it connects successfully.

Is Oracle 9i that different from If we can connect to from a
7.3.3 client, why not to a 9i server?

Any suggestions/thoughts are welcome.