Passing a path as a macro to another project

[kinook]

I have a Visual Build Project that uses a temporary macro %SourceDir% to decide where the check data out to. This works fine if I run the project on its own. However if I try to call that VBP project from another and pass it the %SourceDir% macro from the parent project I get a messagebox that states "The system cannot find the specified file".

If I put some other value in that is not a directory it does not give me this messagebox but still fails because it is not a directory (expected).

Here is the command line that is being called from the VBP project:

"C:\Program Files\VisBuildPro\VisBuildPro.exe" "SourceDir=c:\develop\" /b "C:\develop\Visual Build Pro\FormsPartnerHelp.bld"

How do I pass a directory as a macro?

Thanks in advance,
Eric Eicke