John
I am pretty current SI Connector does not support User Defined Table type. Since it is fairly new and I am not sure if Linq to SQL, Entity Framework support that or not. This will have to be entered as an enhancement request for us to looking into and provide an estimate.
In your screen shot, which field you think is complaining with the error? Do you have stored procedure for the underlying connection used in your screen shot? Can it be accessed from our end?