ListView showing empty TextBlocks at runtime

I'm experiencing a strange problem with data-binding. In the designer everything is shown correctly, but at runtime my ListView just contains those TextBlocks with an empty string in them. I'm using MVVM light for ViewModels. Most of the code was generated by VS2012 by creating a split page for WindowsStore-Apps.

Here's my XAML: ( I already removed some other parts, like the VisualStateManager, but without effect so that doesn't seem to be an issue.)

<common:LayoutAwarePage
    x:Name="pageRoot"
    x:Class="Kunden.OrderPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Kunden"
    xmlns:common="using:Kunden.Common"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    DataContext="{Binding SelectCustomersViewModel, Source={StaticResource Locator}}">

    <Page.Resources>
        <CollectionViewSource
            x:Name="itemsViewSource"
            Source="{Binding Items}"/>
    </Page.Resources>

    <Grid Style="{StaticResource LayoutRootStyle}">
        <Grid.RowDefinitions>
            <RowDefinition Height="140"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition x:Name="primaryColumn" Width="610"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>

        <Grid x:Name="titlePanel">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>
            <Button
                x:Name="backButton"
                Click="GoBack"
                IsEnabled="{Binding DefaultViewModel.CanGoBack, ElementName=pageRoot}"
                Style="{StaticResource BackButtonStyle}"/>
            <TextBlock x:Name="pageTitle" Grid.Column="1" Text="Werbeauswahl" Style="{StaticResource PageHeaderTextStyle}" Margin="0,0,-2,40"/>
        </Grid>

        <!-- Elementliste mit vertikalem Bildlauf -->
        <ListView
            x:Name="itemListView"
            AutomationProperties.AutomationId="ItemsListView"
            AutomationProperties.Name="Items"
            TabIndex="1"
            Grid.Row="1"
            Margin="-10,-10,0,0"
            Padding="120,0,0,60"
            IsSwipeEnabled="False"
            SelectionChanged="ItemListView_SelectionChanged"
            ItemsSource="{Binding AvaiableCountries}">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding Name}"/>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
... closing brackets etc.

The IEnumerableI want to bind:

private IEnumerable<Country> avaiableCountries;

        public IEnumerable<Country> AvaiableCountries
        {
            get { return avaiableCountries; }
            set { avaiableCountries = value; RaisePropertyChanged(() => AvaiableCountries); }
        }

The data value object CountryI need for my LINQ-Query:

public class Country
    {
        internal string Name { get; set; }
    }