处理DataContext和代码分析消息

我刚刚对我们的一个项目进行了代码分析，当我收到以下警告消息时，我有点惊讶;

CA2000: Microsoft。可靠性:在方法'DataImport.ImportSalesExecBackFill(Stream)'中，在对象'dc'的所有引用超出范围之前调用System.IDisposable.Dispose。

引用下面的代码段;

            using (DataDataContext dc = new DataDataContext(ConfigurationManager.ConnectionStrings["data"].ConnectionString))
            {
                List<tableSale> sample = (from s in dc.tableSales
                                                   where bfData.Select(d => d.RegNo).ToList().Contains(s.RegNum)
                                                   select s).ToList();
                var matches = (from s in sample
                               join bfd in bfData on s.RegNum equals bfd.RegNo
                               where string.IsNullOrEmpty(s.OpDesc)
                               select new { UserId = s.UserID, OpId = String.Format("SMMT{0}-{1}", s.DlrNo, bfd.OpName), OpDesc = bfd.OpName }).ToList();
                List<tableSale> updQuery = (from s in dc.tableSales
                                                     where matches.Select(d => d.UserId).ToList().Contains(s.UserID)
                                                     select s).ToList();
                foreach (tableSale rec in updQuery)
                {
                    rec.OpID = matches.Where(s => s.UserId == rec.UserID).Select(s => s.OpId).First();
                    rec.OpDesc = matches.Where(s => s.UserId == rec.UserID).Select(s => s.OpDesc).First();
                }
                dc.SubmitChanges(System.Data.Linq.ConflictMode.ContinueOnConflict);
                using (PCSalesDataContext pcdc = new PCSalesDataContext(ConfigurationManager.ConnectionStrings["LatData"].ConnectionString))
                {
                    List<tblSale> upd700 = (from s in pcdc.tblSales
                                            where matches.Select(d => d.UserId).ToList().Contains(s.UserID)
                                            select s).ToList();
                    foreach (tblSale rec in upd700)
                    {
                        rec.OpID = matches.Where(s => s.UserId == rec.UserID).Select(s => s.OpId).First();
                        rec.OpDesc = matches.Where(s => s.UserId == rec.UserID).Select(s => s.OpDesc).First();
                    }
                    pcdc.SubmitChanges(System.Data.Linq.ConflictMode.ContinueOnConflict);
                }
                result = true;
            }   

现在我的印象是数据上下文总是在using语句的作用域结束时处理。是我错过了什么，还是这是一个我可以愉快地忽略的警告信息?