Hi Leon Condon,
That is unfortunately by design at the moment, as you have to have your classes mapped e.g. there should be columns mapped to each property in your classes. We understand that this is not a good user experience and we are currently working on a major re-design of our associations which will allow user to create associations exactly in the way that you want at the moment. However that functionality is scheduled for the first Service Pack of the Q2 release.
At the moment you can only workaround the behavior by default mapping your classes to tables and your properties to columns. You can do that by selecting an entity on the design surface and checking the 'Use Default Mapping' checkbox in the mapping details editor.
the Telerik team
Q1’11 SP1 of Telerik OpenAccess is available for download
; also available is the Q2'11 Roadmap
for Telerik OpenAccess ORM.