The member with identity ' ' does not exist in the metadata collection.\r\nParameter name: identity

I simplified the code a little while trying to debug: ``` [HttpPost] public ActionResult Register(User model) { DateTime bla = new DateTime(2012, 12, 12); try { User user = new User { gid = 1, cid = 1, firstName = model.firstName, lastName = model.lastName, email = model.email, username = model.username, password = model.password, creationDate = bla, active = 1 }; myContext.Users.AddObject(user); myContext.SaveChanges(); } catch (Exception ex) { throw ex; } return View(); } ``` The values are transmited accordingly. Users table: ``` [id] [int] IDENTITY(1,1) NOT NULL, [cid] [int] NULL, [gid] [int] NULL, [firstName] [nvarchar](100) NOT NULL, [lastName] [nvarchar](100) NOT NULL, [email] [nvarchar](max) NOT NULL, [username] [nvarchar](100) NOT NULL, [password] [nvarchar](100) NOT NULL, [creationDate] [datetime] NOT NULL, [active] [int] NOT NULL, ``` CONSTRAINT [PK_Users_3213E83F0AD2A005] PRIMARY KEY CLUSTERED I deleted all the foreign keys to be sure that nothing affects it. I am qute certain that at a previous moment it was working, but now I can not figure where the issue is. It crashes while performing the savechanges: ``` {"An error occurred while updating the entries. See the inner exception for details."} {"The member with identity '' does not exist in the metadata collection.\r\nParameter name: identity"} ```