You seem to have something strange going on. The common/lib directory was part of Tomcat 5, but no longer exists in Tomcat 6. In Tomcat 6, database driver jars should go in the TOMCAT_HOME/lib directory. Also, classes12 is about 10 years ago and was replaced by the ojdbc14.jar.
An IDE is no substitute for an Intelligent Developer.
Joined: Feb 15, 2013
sir.i tried reinstalling tomcat6 again on my ubuntu..the path is the same..
n still no changes