I give up. I found this: http://blogs.msdn.com/b/adonet/archive/2011/03/15/ef-4-1-model-amp-database-first-walkthrough.aspx And thought, that\'s cool. So I quickly redesigne
Delete or comment this :
//protected override void OnModelCreating(DbModelBuilder modelBuilder) //{ // throw new UnintentionalCodeFirstException(); //}
And change your connection string to valid one.