Sub Menu Not displaying on Remote server Using Menu and Web.Sitemap

Question

I have used menu with web.sitemap similar which  have used in Timetracker starter kit keeping main Node Url blank for every sub menu.
all first urls are blank so that no hover, only sub menu can redirect.

It is working perfectly on local machine but not showing sub menu on server while main Node changes along with differant roles.

Below is web.sitemap and Menu
------
<?xml version="1.0" encoding="utf-8" ?>
<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >
<siteMapNode title="" url="" description="NetIntegrityZone" roles="*" >
<siteMapNode url="~/default.aspx" title="Home" roles="Chairman,Director,Manager,Member,Supervisor,H.R.Manager,H.R.Personnel,Receptionist,Business.Developer,Marketing.Executive"/>

<siteMapNode url="" title="Departments" roles="Director,Manager,Member,Supervisor,H.R.Manager,H.R.Personnel,Receptionist,Business.Developer,Marketing.Executive" >
<siteMapNode url="~/Departments/AddDepartments.aspx" title="Add Department" roles="Director"/>
<siteMapNode url="~/DiMa/DeptDetails.aspx" title="Departments Details" roles="Director,Manager" />
<siteMapNode url="~/Department/SwitchDepartment.aspx" title="Switch Department" roles="Director,Manager,Member,Supervisor,H.R.Manager,H.R.Personnel,Receptionist,Business.Developer,Marketing.Executive"/>
</siteMapNode>

<siteMapNode url="" title="Clients" roles="Chairman,Director" >
<siteMapNode url="~/Clients/AddClients.aspx" title="Add Clients" roles="Chairman,Director" />
<siteMapNode url="~/Clients/ClientDetail.aspx" title=" Client Report" roles="Chairman,Director" />
</siteMapNode>
</siteMapNode>

-----------------------
<asp:SiteMapDataSource runat="server" ID="sitemapDS" ShowStartingNode="false" />
<asp:Menu ID="mainMenu" runat="server" Orientation="Horizontal" DynamicEnableDefaultPopOutImage="false"
MaximumDynamicDisplayLevels="2" DataSourceID="sitemapDS" StaticMenuItemStyle-ItemSpacing="0px"
ItemWrap="true" StaticEnableDefaultPopOutImage="false" />
------------------------