Databinding object to a Windows Form

[Efitap]

Project type is Windows forms application.

I have the following issue:

I want to unit test my GUI as far as I can, thus I wrote:

namespace Presentation
{
	public class LoginForm : INotifyPropertyChanged
	{
		private string _password = string.Empty;

		// Declares an event to fire, should we want to report that a property has changed
		public event PropertyChangedEventHandler PropertyChanged;


		// Case sensitive comparison is performed on the password prior to setting the new value
		public string Password
		{ 
			get { return _password; }
			set 
			{
				if( string.Compare( _password, value, false ) != 0 )
				{
					_password = value;
					if( PropertyChanged != null )
					{
						PropertyChanged( this, new PropertyChangedEventArgs( "Password" ) );
					}
				}
			}
		}


		public bool OkButtonEnabled
		{
			get
			{
				return ! ( string.IsNullOrEmpty( Username ) || string.IsNullOrEmpty( Password ) );
			}
		}
	}
}

(Code chopped for legibility)

Now, I have a corresponding windows form that I want to use this class with, I create the button and text box, and find the databinding controls.

The first time that I reference it, I am asked to create a data binding source, no problem, I navigate through the namespaces and end up with a loginFormBindingSource object.

Then I proceed. In properties for the Password, I bind the text property to the loginFormBindingSource's Password property.

For the button, I go to "advanced" and choose to bind the "Enabled" property to the "OkButtonEnabled" property in the binding source.

Compiling and running is without error, however, the data binding does not work. I must be missing something important, like a constructor, so I tried
to initialize the binding source, but to no avail.

If I remove all GUI bindings and instead opt to bind manually in the form's constructor like this:

public partial class Form1 : Form
{
	LoginForm codeBehindLoginForm	 = new LoginForm( );

	public Form1()
	{
		InitializeComponent();

					
		tbPassword.DataBindings.Add	( "Text",	 codeBehindLoginForm, "Password" );
		btnOk.DataBindings.Add		( "Enabled", codeBehindLoginForm, "OkButtonEnabled" );			
	}
}

...then everything works as expected.

Can anyone please enlighten me as to how I can get the GUI binding, using properties to work? I am almost sure that the only thing missing is some form of initalization, I'm just not sure where. A search here, and on google returns only examples of binding to data sources.
In advance, thanks for reading.