WPF Can´t change content of label by databinding

[Czechtim]

Hello, I have problem with databinding. I created small application using structure that I need to demonstrate problem.
I need to change content of label when changing content of property "Promena". I change content of property "Promena" from "Origin text" to "Changed text" using thread but content of label is still the same - databinding isn´t working according to my vision.
Does somebody know, please, why content of label doesn´t change when I change content of property "Promena"?

test.xaml

<Window x:Class="DispatcherTimer_CodeProject.test" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"   
        xmlns:src="clr-namespace:DispatcherTimer_CodeProject" 
        x:Name="myDispatcherTimer" 
        Title="DispatcherTimer" 
        WindowStyle="None" 
        WindowState="Maximized" 
        ResizeMode="NoResize">  
 
    <Window.Resources>    
        <src:test x:Key="prevod"/>  
        <DataTemplate x:Key="grid1">  
            <Grid x:Name="myGrid" Background="Blue" Cursor="None">  
                <Grid.RowDefinitions> 
                    <RowDefinition Height="*"/>  
                    <RowDefinition Height="*"/>  
                </Grid.RowDefinitions> 
                <Grid.ColumnDefinitions> 
                    <ColumnDefinition/> 
                </Grid.ColumnDefinitions> 
                <Label Grid.Row="0"    
               Grid.Column="0"    
                       Name="DatumCas2" 
               Content="{Binding Source={StaticResource prevod}, Path=Promena, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" 
               VerticalContentAlignment="Center"   
               HorizontalContentAlignment="Center">  
                </Label> 
            </Grid> 
        </DataTemplate> 
        <DataTemplate x:Key="grid2">  
            <Grid x:Name="myGrid" 
          Background="Black" 
          Cursor="None">  
                <Grid.RowDefinitions> 
                    <RowDefinition Height="*"/>  
                    <RowDefinition Height="*"/>  
                </Grid.RowDefinitions> 
                <Grid.ColumnDefinitions> 
                    <ColumnDefinition/> 
                </Grid.ColumnDefinitions> 
 
                <Label Grid.Row="0"   
               Grid.Column="0"   
               Foreground="Red" 
               FontSize="50" 
               Content="CurrentDateAndTime" 
               VerticalContentAlignment="Center" 
               HorizontalContentAlignment="Center">  
                </Label> 
                <Label x:Name="DatumCas" 
               Grid.Row="1" 
               Grid.Column="0" 
               Foreground="White" 
               FontSize="30" 
               VerticalContentAlignment="Top" 
               HorizontalContentAlignment="Center">  
                </Label> 
            </Grid> 
        </DataTemplate> 
    </Window.Resources> 
</Window> 

test.xaml.cs

using System;  
using System.Windows;  
using System.Windows.Controls;  
using Microsoft.Win32;  
using System.Windows.Input;  
using System.Threading;  
using System.ComponentModel;  
using System.Windows.Threading;  
 
namespace DispatcherTimer_CodeProject  
{  
    public partial class test : Window, INotifyPropertyChanged  
    {     
        public event PropertyChangedEventHandler PropertyChanged;  
 
        private void NotifyPropertyChanged(string info)  
        {  
            if (PropertyChanged != null)  
                PropertyChanged(this, new PropertyChangedEventArgs(info));  
        }  
 
        private string promena;  
 
        public string Promena  
        {  
            get { return promena; }  
            set { promena = value; NotifyPropertyChanged("Promena"); }  
        }  
 
        public test()  
        {  
 
            InitializeComponent();  
            Promena = "Origin text";  
            this.MouseDoubleClick += new System.Windows.Input.MouseButtonEventHandler(test_MouseDoubleClick);  
            this.ContentTemplate = FindResource("grid1") as DataTemplate;  
        }  
 
        void test_MouseDoubleClick(object sender, System.Windows.Input.MouseButtonEventArgs e)  
        {  
           myDispatcherTimer.Close();  
        }  
 
        private void UserControl_Loaded(object sender, RoutedEventArgs e)  
        {  
            System.Threading.Thread t = new Thread(new ThreadStart(Run));  
            t.SetApartmentState(ApartmentState.STA);  
            t.Start();  
        }  
 
        void Run()  
        {  
            Thread.Sleep(2000);  
            Promena  = "Changed text";  
        }  
    }      
}