Unfortunately this function is currently not yet implemented for free storage location, if you are a developer you can try and implement it using article storage location function as an example, but you might need to add some more checks to get the right table. Accidentaly I had a similar problem today with User note http://www.seblod.com/resources/tracker/17466
If it would be possible to have the compled CRUD cycle on free tables, too - you could use SEBLOD outside thinking in Joomla Articles and Users. Very valuable if you hack on existing database tables (i.e. of other Joomla extensions) or do some real database modeeling. I would very much appreciate this function.