Hi,
Thank your for posting your query,
Final Error Description: "Does agent version 5.026 support Oracle 7.3.4?"
No, It won't support.
The 5.022, 5.025 and 5.026 versions of the Oracle agent are compatible with Backup Exec for Windows NT and Windows 2000 version 8.6, which includes support for Oracle 9i, as well as Backup Exec 9.0 for Windows Servers.
For more information Please check the Software Compatibility List.
http://seer.support.veritas.com/docs/261695.htm
We hope this information helps, if you have any other questions please respond to the post and we will be more than happy to assist you further.
Regards