9i R2 does not connect to v7 database
I remember reading something from Oracle that stated with 9i Release 2, development has desupported connecting to or from either a 7.3.4 client or server. There is no workaround. This is listed in the sqlplus readme doc.
I have not tried this myself as I just received 9i R2, but have not installed it anywhere. I will need to look into this as well as I still have some old production systems running under 7.3.4. If I need to, I guess I can upgrade them and run them under a 7.3 compatible mode and see if that works ok. If you try this please let us know what the results are.