oracle 7.3 , delphi 3.02 connectivity : problem

I can't make a connection to Oracle Workgroup Server 7.3.4,
running on Win NT4.0 .

Im using delphi 3.02 C/S, following happens:

I can see the database name in the BDE section "database name" ex.:
but after trying to login ,I get following error:

Error # 15879
Vendor initialization failed.

regardless of using TCP/IP or TNS

The Problem is on BDE's site, I can connect to oracle with an Oracle

can somebody give me a hint?