[Zope] Debugging Zope (again)

I'm still totally lost when it comes to the debugger. I'm not able to set a working breakpoint. I can steps through the code, and I notice that the point where I have set the breakpoint is reached. But yet, when I do a 'continue' it never stops at the breakpoint. Could somebody plese give me a step by step instruction on how to set a breakpoint with the pdb, so I can figure out what I'm doing wrong? I'm using Zope 2.3.3 on Windows 98.