How to debug .java file in E-Commerce

Hi Experts, again I need your help:

I tried to debug into the code of an action (.java) file in E-Commerce but my Debug prospective did not work. Here is what I did:

1) enable debugging of process for local J2EE engine

2) setup a line breakpoint

3) select Debug prospective

4) run b2b application http://localhost:50200/b2b/b2b/init.do? (should I put some debug paramenter in this url?)

Can anyone advise me what's wrong / what I missed?

Thanks, Jin