Move item from Listbox to another (2)

Create new Website and in Default.aspx add two Listbox (lstEmployees , lstSelectedEmployees) and in lstEmployees Listbox add items and add four buttons (<< ,>>,<,>) with Id's
(btn_AddAll,btn_RemoveAll,btn_Add,btn_Remove)

and in Default.aspx.cs

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Default2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}

protected void btn_Add_Click(object sender, EventArgs e)
{
if (lstEmployees.SelectedIndex > -1)
{
//Gets the value of items in list.

string _value = lstEmployees.SelectedItem.Value;
// Gets the Text of items in the list.
string _text = lstEmployees.SelectedItem.Text;
//create a list item
ListItem item = new ListItem();
//Assign the values to list item
item.Text = _text;
item.Value = _value;
//Add the list item to the selected list of employees

lstSelectedEmployees.Items.Add(item);
//Remove the details from employee list

lstEmployees.Items.Remove(item);

}
}

protected void btn_Remove_Click(object sender, EventArgs e)
{
if (lstSelectedEmployees.SelectedIndex > -1)
{
//Gets the value of items in list.
string _value = lstSelectedEmployees.SelectedItem.Value;
//Gets the Text of items in the list.
string _text = lstSelectedEmployees.SelectedItem.Text;
//create a list item
ListItem item = new ListItem();
item.Text = _text;
//Assign the values to list item
item.Value = _value;
//Remove from the selected list
lstSelectedEmployees.Items.Remove(item);
//Add in the Employee list
lstEmployees.Items.Add(item);
}

}

protected void btn_AddAll_Click(object sender, EventArgs e)
{
int _count = lstEmployees.Items.Count;
if (_count != 0)
{
for (int i = 0; i < _count; i++)
{
ListItem item = new ListItem();
item.Text = lstEmployees.Items[i].Text;
item.Value = lstEmployees.Items[i].Value;
//Add the item to selected employee list
lstSelectedEmployees.Items.Add(item);
}

}

//clear employee list
lstEmployees.Items.Clear();


}

protected void btn_RemoveAll_Click(object sender, EventArgs e)
{
int _count = lstSelectedEmployees.Items.Count;
if (_count != 0)
{
for (int i = 0; i < _count; i++)
{
ListItem item = new ListItem();
item.Text = lstSelectedEmployees.Items[i].Text;
item.Value = lstSelectedEmployees.Items[i].Value;
lstEmployees.Items.Add(item);
}
}
//clear the items
lstSelectedEmployees.Items.Clear();
}
}