The problem is that there is a difference between the version of OpenAccess used to create the project and the one installed on your machine. Since the Q3 2009 release Telerik OpenAccess ORM is equipped with a powerful upgrade wizard which can be used to update the versions of all project references and assembly directives. You can run it by navigating to Telerik-> OpenAccess-> Configuration-> Check Settings...
When the wizard appears you should just click Check
. A list of results for each check will be generated. The version related problems can be fixed by clicking on the Fix
Hope that helps.
the Telerik team