Query String truncated from top navigation bar

I'm trying to update top navigation node URL while I'm creating site programmatically from custom template using below code, but for some reason querystring removed by sharepoint , however, SharePoint Server Publishing Infrastructure feature is enabled in site collection as well in custom site template SharePoint Server Publishing feature in enabled

SPWeb web = site.AllWebs[SiteName];

 web.AllowUnsafeUpdates = true;


 foreach (SPNavigationNode TopNode in web.Navigation.TopNavigationBar)
 {
   TopNode.Properties["UrlQueryString"] = "p=" + ProjectNo;
  TopNode.Update();
 }       
web.AllowUnsafeUpdates = false;