Referencing business rule in data management step

I'm struggling with something elementary here. I can't seem to properly reference a business rule in my data managment step. I've tried a couple of options - explicit workspace name and 'Current' which should both work, but I consistently get the error:

Error processing Data Management Step 'MyDMStep'. Business Rule 'Workspace.MyWorkspace.MyAssy.MyBR' is invalid.

or

Error processing Data Management Step 'MyDMStep'. Business Rule 'Workspace.Current.MyAssy.MyBR' is invalid.
Using that name as a reference, this is how my App Workspace Heirarchy looks:

Anyt input would be greatly appreciated!