New Post: Entity's state isn't updated

Class FLContext : Inherits DbContext

    Property Districts As DbSet(Of District)
    Property Producers As DbSet(Of Producer)

    SubNew()
    EndSubSubNew(nameOrConnectionString AsString)
        MyBase.New(nameOrConnectionString)
    EndSubProtectedOverridesSub OnModelCreating(modelBuilder As DbModelBuilder)
        With modelBuilder.Configurations
            .Add(New DistrictConfiguration)
            .Add(New ProducerConfiguration)
        EndWithEndSubEndClassClass DistrictConfiguration : Inherits EntityTypeConfiguration(Of District)
    SubNew()
        ToTable("District")
        HasKey(Function(p) p.Id)
        [Property](Function(p) p.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None)
    EndSubEndClassClass ProducerConfiguration : Inherits EntityTypeConfiguration(Of Producer)
    SubNew()
        ToTable("Producer")
        HasKey(Function(p) p.Id)
        [Property](Function(p) p.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None)
    EndSubEndClassClass District
    OverridableProperty Id AsIntegerOverridableProperty Num AsIntegerEndClassClass Producer
    OverridableProperty Id AsIntegerOverridableProperty Num AsIntegerEndClass

Sub TestCodeFirst()

    Dim server = New SqlServer(ServerEnum.Local)
    db = New FLContext(server.ConnectionString)
    db.Database.Initialize(True)

    Console.WriteLine("Properties:")
    Console.WriteLine("AutoDetectChangesEnabled: {0}", db.Configuration.AutoDetectChangesEnabled)
    Console.WriteLine("LazyLoadingEnabled: {0}", db.Configuration.LazyLoadingEnabled)
    Console.WriteLine("ProxyCreationEnabled: {0}", db.Configuration.ProxyCreationEnabled)
    Console.WriteLine("ValidateOnSaveEnabled: {0}", db.Configuration.ValidateOnSaveEnabled)
    Console.WriteLine()

    ' Delete any existing data
    db.Database.ExecuteSqlCommand("delete from dbo.District;", {})
    db.Database.ExecuteSqlCommand("delete from dbo.Producer;", {})

    Console.WriteLine("Adding districts...")
    With db.Districts
        .Add(New District With {.Id = 1, .Num = 11})
        .Add(New District With {.Id = 2, .Num = 44})
    EndWith

    db.SaveChanges()

    Console.WriteLine("Changing Num property for District with Id = 2...")
    Dim dist = db.Districts.Where(Function(d) d.Id = 2).First()
    Dim entry = db.Entry(dist)
    Console.WriteLine("The state when retrieved: {0}", entry.State)
    ' Change "Num" property
    dist.Num = 22
    'db.ChangeTracker.DetectChanges()
    Console.WriteLine("The state when changed: {0}", entry.State) 'Should be "Modified"
    db.SaveChanges()

EndSub