Windows store 8.1 dynamic binding not updating in UI - data-binding

Question

I have made a simple test for updating binded values in the UI but nothing seems to update, only intial values are set but never updated, what would i be missing?
code:
//the model class
public class DemoCustomer : INotifyPropertyChanged
{
// These fields hold the values for the public properties.
private Guid idValue = Guid.NewGuid();
private string customerNameValue = String.Empty;
private string phoneNumberValue = String.Empty;
public event PropertyChangedEventHandler PropertyChanged= delegate { };
// This method is called by the Set accessor of each property.
// The CallerMemberName attribute that is applied to the optional propertyName
// parameter causes the property name of the caller to be substituted as an argument.
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
// The constructor is private to enforce the factory pattern.
public DemoCustomer()
{
customerNameValue = "Customer";
phoneNumberValue = "[phone]";
}
// This is the public factory method.
public static DemoCustomer CreateNewCustomer()
{
return new DemoCustomer();
}
// This property represents an ID, suitable
// for use as a primary key in a database.
public Guid ID
{
get
{
return this.idValue;
}
}
public string CustomerName
{
get
{
return this.customerNameValue;
}
set
{
if (value != this.customerNameValue)
{
this.customerNameValue = value;
NotifyPropertyChanged();
}
}
}
public string PhoneNumber
{
get
{
return this.phoneNumberValue;
}
set
{
if (value != this.phoneNumberValue)
{
this.phoneNumberValue = value;
NotifyPropertyChanged();
}
}
}
}
Then simply in my main page i do this:
public ObservableCollection<DemoCustomer> progcollection = new ObservableCollection<DemoCustomer>();
public MainPage()
{
this.InitializeComponent();
progcollection = new ObservableCollection<DemoCustomer>();
this.progcollection.Add(new DemoCustomer());
this.txtblk.DataContext = progcollection[0].CustomerName;
}
Then in a click listener for example i do this:
private void Button_Click_1(object sender, RoutedEventArgs e)
{
progcollection[0].CustomerName = "we changed the name!";
}
But nothing updates in the UI!!!
And here is my XAML:
<Page
x:Class="downloadprogressbinding.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:simpledownload"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<TextBlock x:Name="txtblk" HorizontalAlignment="Left" Margin="994,421,0,0" TextWrapping="Wrap" Text="{Binding Mode=TwoWay}" VerticalAlignment="Top" Height="89" Width="226" FontSize="36"/>
<Button Content="Button" HorizontalAlignment="Left" Height="51" Margin="116,24,0,0" VerticalAlignment="Top" Width="407" Click="Button_Click_1"/>
</Grid>

Answer 1

Using path keyword in binding and specifying the field solved it,like this:
{Binding Path=thetext, Mode=TwoWay}