خطای 

Value cannot be null.
Parameter name: value

 public virtual ActionResult Index()
        {
                 var persons = new List<Person>()
            {
                     new Person() {Id = 1, FirstName = "sadar", LastName = "marvati", Gender = true}
                     , new Person() {Id = 2, FirstName = "omid", LastName = "nasri", Gender = true}
                      , new Person() {Id = 3, FirstName = "hana", LastName = "akbari", Gender = false}
                       , new Person() {Id = 4, FirstName = "ali", LastName = "jahani", Gender = true }
                        , new Person() {Id = 5, FirstName = "sara", LastName = "sabori", Gender = false }
             };
            // 
            StiReport report = new StiReport();
            string Path = Server.MapPath("~/Reports/Report.mrt");
            report.Load(Path);
            report.Compile();
            return StiMvcViewer.GetReportSnapshotResult(HttpContext, report);

            //return View();
        }