Ant Debug Issue - Attaching Source: What is the correct approach?

I have a simple project setup as follows:

- In IDEA, Project A has a "module dependency" on Project B, and is setup as "compile" scope.
- In Ant, I have a target that runs Project A junits in debug mode.
- In IDEA, I have a remote debug configuration setup to connect to Ant.
- In IDEA, I have a breakpoint in the source code for Project A.

My run procedure is as follows:

- I start my remove debug configuration.
- I start my Ant junits target.

So, here the debugger stops on the breakpoint in Project A correctly.  However, when I'm stepping through and I get to some code that is in Project B, it says I need to attach source code.  Shouldn't it know where to look for the source code based on the module dependency I setup?  What would I even attach source code to?

Any help is appreciated.

Thanks.