ASP.Net Menu Control Menu Click event not working in VB.Net

dear fellas, 

i have this code. 

<asp:Menu ID="rootmenu" runat="server" CssClass="linkLableName" Width="156px"

ForeColor="#ffffff" Orientation="horizontal" StaticMenuItemStyle-CssClass="menuItem"

DynamicMenuItemStyle-CssClass="menuItem" OnMenuItemClick="rootmenu_MenuItemClick">

 <Items>

<asp:MenuItem Value="Home" NavigateUrl="~/Main/MainPage.aspx" /> </Items>
                                             
<DynamicHoverStyle CssClass="linkLableNameItem" />
<DynamicMenuStyle CssClass="linkLableNameItem" />
<DynamicSelectedStyle CssClass="linkLableName" />
<DynamicMenuItemStyle CssClass="linkLableNameItem" /> 
                                               
 <Items>

asp:MenuItem Text="Log Out" Value="logout" ToolTip="Log Out"/></Items>           

</asp:Menu></td>

Protected Sub rootmenu_MenuItemClick(ByVal sender As Object, ByVal e As MenuEventArgs)
        Select Case e.Item.Value
            Case "logout"
                Session.Abandon()
                Session("validusr") = Nothing
                Response.Redirect("~/default.aspx")
        End Select
    End Sub

but i cant get it work. do u have any idea where i might wrong?