INotifyPropertyChanged.PropertyChanged always NULL - wpf

Question

I know I am doing something wrong here but what. Please have a look and point out my error.
I will see "Peter" in my textbox but no "Jack" after the button click.
My class
namespace App
{
class Person : INotifyPropertyChanged
{
private string name;
public String Name
{
get { return name; }
set { name = value; OnPropertyChanged("Name"); }
}
public Person()
{
Name = "Peter";
}
public void SetName(string newname)
{
Name = newname;
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string prop)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(prop));
}
}
}
}
My XAML
<Window x:Class="test.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:app="clr-namespace:App"
Title="MainWindow" Height="400" Width="400">
<Grid>
<Grid.Resources>
<app:Person x:Key="person"/>
</Grid.Resources>
<TextBox Width="100" Height="26" Text="{Binding Source={StaticResource person}, Path=Name, Mode=TwoWay}" />
<Button Content="Button" Height="23" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
</Grid>
And my codebehind
public partial class MainWindow : Window
{
Person person;
public MainWindow()
{
InitializeComponent();
person = new Person();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
person.SetName("Jack");
}
}
Thanks.

Answer 1

You have two instances of Person. PropertyChanged is not null in the static resource
This isn't really what StaticResources are for. Get rid of the static resource, change the binding to:
{Binding Path=Name, Mode=TwoWay}
and add this to your constructor:
DataContext = person;

Answer 2

That object person in codebehind of MainWindow is not the same object you have binding to in XAML
If you want to use that object from resources you have to find it in code behind so something like this in constructor
person = (Person)Resources["person"];