Sorry, I don't really use Oracle and Weblogic so I can't say for sure, but the error message and location REALLY look like you don't have your DB connection information set up correctly.
Common things that come to mind might be
JDBC driver versions and security issues (e.g. the DB user you are using doesn't have the right to connect from that machine, etc). If you are using a JNDI datasource for your DB access, sometimes the URLs for these can be tricky.
Have you tried just writing a simple
jsp page to access the DB using the standard JDBC calls from the jForum web context? This sometimes can give you more information about what is going wrong and if it's a jForum or just connection issue.
FWIW, I'm not sure, but I think there are people using WL and Oracle...
[originally posted on jforum.net by monroe]