Access BaseView Model Data in Layout using Global ActionFilters in ASP.Net MVC

Accessing BaseViewModel Data in _Layout.cshtml using Global ActionFilters

I am trying to access BaseViewModel data in _Layout.cshtml using global action filter.

I am able to access baseviewmodel data in HomeController but not in the AccountController. I am getting a NullReferenceException in the below line.

baseViewModel.SiteName = siteSettings.SiteName;

All my viewmodel class are inheriting from the baseviewmodel class.

I am using the correct override? Should I use OnActionExexcuting or OnResultExecuting?

Please guide me.

    public class LoadSiteSettingsAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuted(ActionExecutedContext filterContext)
        {
            if(filterContext.Result is ViewResult)
            {
                var baseViewModel = filterContext.Controller.ViewData.Model as BaseViewModel;
                SiteSettingsService siteSettingsService = new SiteSettingsService();
                var siteSettings = siteSettingsService.GetSiteSettings(1);
                baseViewModel.SiteName = siteSettings.SiteName;
                baseViewModel.IsRegister = siteSettings.IsRegister;
                baseViewModel.SiteFooter = siteSettings.SiteFooter;
                baseViewModel.LogoURL = siteSettings.LogoURL;
                baseViewModel.FaviconURL = siteSettings.FaviconURL;
                baseViewModel.IsDNSPrefetchOn = siteSettings.IsDNSPrefetchOn;
                baseViewModel.SiteAuthor = siteSettings.SiteAuthor;
                baseViewModel.DNSPrefetch = siteSettings.DNSPrefetch;
                baseViewModel.DNSPreconnect = siteSettings.DNSPreconnect;
                baseViewModel.GoogleSiteVerification = siteSettings.GoogleSiteVerification;
                baseViewModel.GoogleAnalytics = siteSettings.GoogleAnalytics;
                baseViewModel.CustomCSS = siteSettings.CustomCSS;
                baseViewModel.CustomJavaScript = siteSettings.CustomJavaScript;
                baseViewModel.IsUnderMaintenance = siteSettings.IsUnderMaintenance;
            }
        }
    }