What version of Oracle are you using?
You might want to check the B2B Server classpath. Look for classes111.zip and classes12.zip. If both are there you have multiple version of the JDBC driver. When resolving which driver to use, the JVM will take the one that appears first in the classpath, and that one may be incompatible with the version of Oracle you are using.
#Integration-Server-and-ESB#Adapters-and-E-Standards#webMethods