private void LoadDirtyRooms()
 {
     DataSet dsDirtyRooms = new RoomDAO().SelectAllDirtyRooms(Master.CurrentCompany.CompanyId);
     dsDirtyRooms.Tables[0].PrimaryKey = new DataColumn[] { dsDirtyRooms.Tables[0].Columns["RoomId"] };
     Session[Constants.SESSION_DIRTYROOMS] = dsDirtyRooms;
     if (dsDirtyRooms.Tables[0].Columns.Contains("CleanedDate") == false)
     {
         dsDirtyRooms.Tables[0].Columns.Add("CleanedDate", Type.GetType("System.DateTime"));
     }
     gvDirtyRooms.DataSource = (DataSet)Session[Constants.SESSION_DIRTYROOMS];
     gvDirtyRooms.DataBind();
 }