C# data binding doesn't update WPF

<ObjectDataProvider x:Key="PhoneServiceDS"
    ObjectType="{x:Type kudu:PhoneService}" d:IsDataSource="True"/>

<Label x:Name="DisplayName" Content="{Binding
    Path=MyAccountService.Accounts[0].DisplayName, Mode=OneWay,
    Source={StaticResource PhoneServiceDS}}"/>

Binding displayNameBinding = new Binding();
     displayNameBinding.Source =
         PhoneService.MyAccountService.Accounts[0].DisplayName;
     displayNameBinding.Mode = BindingMode.OneWay;
     this.DisplayName.SetBinding(Label.ContentProperty, displayNameBinding);

Binding displayNameBinding = new Binding( "MyAccountService.Accounts[0].DisplayName" );
displayNameBinding.Source = new ObjectDataProvider { ObjectType = typeof(PhoneService), IsDataSource = true };
displayNameBinding.Mode = BindingMode.OneWay;
this.DisplayName.SetBinding(Label.ContentProperty, displayNameBinding);

Binding displayNameBinding = new Binding();
     displayNameBinding.Source = PhoneService;
     displayNameBinding.Path = "MyAccountService.Accounts[0].DisplayName";
     displayNameBinding.Mode = BindingMode.OneWay;
     this.DisplayName.SetBinding(Label.ContentProperty, displayNameBinding);