Radrails: workspace in use, choose a different one

I've just begun using Radrails and am experiencing a puzzling error. When I set my workspace to my home directory/some subdirectory, Radrails starts correctly. I would like to set the workspace to /var/rails where I have all of my existing rails apps but Radrails fails to start with the error: workspace in use, choose a different one. Any ideas? I want to edit the code in the directory in which it runs, thereby avoiding copying the modded code to the executable directory.

Thanks