The main problem is that I recieve the following message:

"base {System.SystemException} = {"Unable to create a constant value of type 'BokButik1.Models.Book-Author'. Only primitive types ('such as Int32, String, and Guid') are supported in this context."}"

based on this LinQ code:

IBookRepository myIBookRepository = new BookRepository();
var allBooks = myIBookRepository.HamtaAllaBocker();

IBok_ForfattareRepository myIBok_ForfattareRepository = new Bok_ForfattareRepository();
var Book-Authors = myIBok_ForfattareRepository.HamtaAllaBok_ForfattareNummer();

var q =
from booknn in allBooks
join Book-Authornn in Book-Authors on booknn.BookID equals Book-Authornn.BookID
select new { booknn.title, Book-AuthorID };

How shall I solve this problem to get a class instance that contain with property title and Book-AuthorID?

// Fullmetalboy

I also have tried making some dummy by using "allbooks" relation with Code Samples from the address http://www.hookedonlinq.com/JoinOperator.ashx. Unfortunately, still same problem.

I also have taken account to Int32 due to entity framework http://msdn.microsoft.com/en-us/library/bb896317.aspx. Unfortunatley, still same problem.

Using database with 3 tables and one of them is a many to many relationship. This database is used in relation with entity framework

Book-Author

Book-Author (int)
BookID (int)
Forfattare (int)

Book

BookID (int)
title (string)
etc etc etc