Say you select a space in AutoCAD Architecture and select Update Space Geometry>Selected Spaces and it does not work.
You may see this on the command line:
No valid boundaries generated.
Select the lines and set Bound spaces to Yes. This is a new thing in ACA 2009.
Now try again and it will work as expected.
No valid boundaries generated can also be seen if the objects forming the boundary is not closed.
One user has also reported that he does not have the Bound spaces option available in ACA 2009 for some reason. Any idea why?