>>The exeption says it all. You are requiring a return type of ClientAPI.ClientService.Client but the select is generating an anonymous type.
>
>The OfType approach was needed. See message #1540670 for more info.

That makes no sense to me. If you are assigning to a type of ClientAPI.ClientService.Client then the result must be of that type (or derived from it). In your code that would not be the case. Can you post enough code to show a working example....