How are the 2 persistent models related? There seems to be a reference field between classes of the 2 models (based on the FK constraint : ref_cstmr_pymnt_mthds_customer)
Can you run the 'Check Settings' wizard (Telerik->OpenAccess->Configuration->Check Settings menu entry) and fix any reported problems? The wizard will ensure that the right entries are made in the app.config. My guess is that the dependency between the 2 models is not set in the config file.
If you can send us a sample project that would help in providing a solution sooner.
All the best,
the Telerik team