Judging by your other ticket (#663257) I am led to believe the problem is most likely connected with the way you have defined your model.
Whenever you have a base class and you get the exception that there is no certain field defined in the given class the only way to workaround that is to specify the full field name in the format (BaseType.fieldName). This way you will not need to have a TempId in your inheritor.
Please try that and see if that fixes your problem.
the Telerik team
Q3'12 SP1 of OpenAccess ORM packs Multi-Table Entities mapping support. Check it out.