Room Separator not working

[jfjacques]

I'm trying to create room using only room separators, so that I can calculate an area on my sheet. 

When i go to tag it nothing shows up. 

[ToanDN]

You still need to place a room inside each boundary.

[Corsten.Au]

If you have split levels, then create Room Separator Lines in Corresponding Levels...

[Anonymous]

I am having the same problem. If I create a simple rectangle wall, and wish to change the dimensions of one wall AFTER I have changed the witness lines to say, the exterior faces, the dimensions in the drawing will actually change, BUT I will get the error message "Can't change dimension segment to this value." It forces me to click "Cancel" to remove the error, and the drawing goes back to the previous unchanged dimension.

I have tried making the rectangle a room before making the above changes, and the same error occurs. If this is not a bug, I don't know what is.