Listbox KeyDown event is not getting Execute

I have setup that when i press Keydown on  itemValueTxt(TextBox Name) it should focus on on my listbox which i name as itemListShow on index 0 and than i create this method itemListShow_KeyDown and i want to go through all items on itemListShow.

BUT

the problem is that after execution of  itemValueTxt_KeyDown method the control is not moving at all to this method itemListShow_KeyDown.there is not erroe appearing the control remain only on 0 Index not moving to next items

Please help me to know what i really missing. 

 

private void itemValueTxt_KeyDown(object sender, KeyEventArgs e)

{

if (e.KeyCode == Keys.Down)

{

itemListShow.Focus();

itemListShow.SelectedIndex = 0;

}

}

private void itemListShow_KeyDown(object sender, KeyEventArgs e)

{

if (e.KeyCode == Keys.Down)

{

this.itemListShow.SelectedIndex = this.itemListShow.SelectedIndex;

}

if (e.KeyCode == Keys.Up)

{

this.itemListShow.SelectedIndex = this.itemListShow.SelectedIndex;

}

}