CheckListBox in ASP.Net

<asp:CheckBoxList ID="CheckBoxList1" runat="server">
            <asp:ListItem Selected="True">FirstCheckBox</asp:ListItem>
            <asp:ListItem>SecondCheckBox</asp:ListItem>
            <asp:ListItem>ThirdCheckBox</asp:ListItem>
            <asp:ListItem>FourthCheckBox</asp:ListItem>
        </asp:CheckBoxList>
        <br />
        <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Reset" />

protected void Button1_Click(object sender, EventArgs e)
    {
        for (int i = 0; i < CheckBoxList1.Items.Count; i++)
        {
            CheckBoxList1.Items[i].Selected = false;
        }
    }