unable to load Mysql DB

I have programs like jsp and beans in JSWDK-1.0.1.and they connect to MySQL. They are working well.
But, after installing the latest version of Tomcat, I run the same program.Error messages are shown.
" Unable to load MySQL DB driver
java.lang.ClassNotFoundException......"
I have tried some simple JSP and beans without connecting to the database. They are working.
Any configuation I am missing ?
Thanks

I have found the answer.
The Tomcat can't refer the mysql.jar under the directory of jdk/jre/mysql/mysql.jar.
I have copy mysql.jar to tomcat4.1\common\lib\mysql.jar.
After doing that, my program can work.