problem with Autocomplete and Leave focus event

[Builder]

I made a simple app to test Leave focus event and AutoComplete
functionality on the text box control. I added 2 text box controls on
the blank form. Then I added Leave focus event handlers for these text
boxes, set AutoCompleteMod e property to SuggestAppend and
AutoCompleteSou rce property set to CustomSource.
AutoCompleteCus tomSource property is changed in a Leave focus event
handlers for each text box, see code below. When I run the application
and changed focus with TAB key, focus still stood on the first text
box. Simply said, it is impossible to change focus with TAB key. Any
suggestions how to solve this problem?

public partial class Form1 : Form
{
AutoCompleteStr ingCollection textBox1AutoCom pleteCollection =
new AutoCompleteStr ingCollection() ;
AutoCompleteStr ingCollection textBox2AutoCom pleteCollection =
new AutoCompleteStr ingCollection() ;

public Form1()
{
InitializeCompo nent();
}

private void InitializeAutoC omplete()
{
textBox1AutoCom pleteCollection .Clear();
textBox2AutoCom pleteCollection .Clear();

textBox1AutoCom pleteCollection .Add("Sunday");
textBox1AutoCom pleteCollection .Add("Monday");
textBox1AutoCom pleteCollection .Add("Tuesday") ;
textBox1AutoCom pleteCollection .Add("Wednesday ");
textBox1AutoCom pleteCollection .Add("Thursday" );
textBox1AutoCom pleteCollection .Add("Friday");
textBox1AutoCom pleteCollection .Add("Saturday" );

textBox2AutoCom pleteCollection .Add("Peter");
textBox2AutoCom pleteCollection .Add("John");
textBox2AutoCom pleteCollection .Add("Martin");
textBox2AutoCom pleteCollection .Add("George");

textBox1.AutoCo mpleteCustomSou rce =
textBox1AutoCom pleteCollection ;
textBox2.AutoCo mpleteCustomSou rce =
textBox2AutoCom pleteCollection ;
}

private void Form1_Load(obje ct sender, EventArgs e)
{
InitializeAutoC omplete();
}

private void textBox1_Leave( object sender, EventArgs e)
{
InitializeAutoC omplete();
}

private void textBox2_Leave( object sender, EventArgs e)
{
InitializeAutoC omplete();
}
}