awx replace datetime

var asbhjsbdja = (from x in col.FindAll().OrderByDescending(d => d.CreatedAt)
                              group x by new { x.ReqFormNo, x.ReqFormDesc }
                              into xx
                              select new { RFN = xx.Key.ReqFormDesc, RFD = xx.Key.ReqFormDesc, MS = xx.Max(x => x.CreatedAt)}).ToList();