ASP.Net MVC Error: Specified cast is not valid

Dear Support,

I am getting this error:Specified cast is not valid.

pleas assist me, see my code below

Thanks

        public ActionResult Reports()
        {            
            var reportData = new List<ACTB_DAILY_LOG>();
            using (actb_daily_logEntities dc = new actb_daily_logEntities())
            {
                reportData = dc.ACTB_DAILY_LOG.ToList();
            } 
            return View(reportData);
        }