How to set a breakpoint on the egg packaged python file?

Hi~

How do I set a breakpoint to a file in the egg?

I met the the following error message.
"pydev debugger: warning: trying to add breakpoint to file that does not exist: /Library/Python/2.7/site-packages/multitask-0.2.0-py2.7.egg!/multitask.py (will have no effect)"

Thanks.