jar file confusion...

Strangely, I find myself in a situation where a class file that I'm putting into a Jar is not found.
The jar is in the classpath explicitly.
The file is in package com.intown.bg.jdbc and is compiled to the appropriate directory (d:\jdk1.3\lib\com\intown\bg\jdbc). If the file is compiled and left in that directory, the program runs fine. But it shouldn't NEED to be there if it's in a jar, right?
What should I check for?

There are a few things you should check.
(Firstly can you show what your classpath looks like?, and the code from which you call this class)
in the meantime check that your class file in your jar file is in a corresponding file structure to it package name.

Whew! I think the problem lies in my inability to set the classpath when running Tomcat.
Does anyone know how to do that? Thanks in advance.