driver class problem

[Nhlanhla Dlamini]

I'm trying to run an application on Tomcat. It fails to run, throwing a null driver class exception. I've already copied a jar file with a Db2 driver class into Tomcat's /common/lib directory. But it still throws the same exception. What might be the problem here? (I would appreciate a detailed explanation).
The exception is:
java.sql.SQLException Cannot load JDBC driver class 'null'
at org.apache.commons.dbpc.BasicDataSource.createDataSource(...)
at org.apache.commons.dbpc.BasicDataSource.getConnection(...)
etc...

[Mike Curwen]

This is a repeated question, and will be continued here