RIA Service 从数据库取不到数据，但做插入操作是可以的？该如何处理

 public void DrawLine()
        {
           
            DeepEarthDemo.Web.DomainService1 client = new DeepEarthDemo.Web.DomainService1();
            DeepEarthDemo.Web.WaterMeter waterMeter = new DeepEarthDemo.Web.WaterMeter();
           
            var sel = from s in client.WaterMeters where s.ID == 1 select s;
            if (sel.Count() == 0)
                return;
            DeepEarthDemo.Web.WaterMeter wm = sel.First();
            string str = wm.PointList;
            MatchCollection matchs = Regex.Matches(str, @"\d+");
            List<Point> points = new List<Point>();

            for (int i = 0; i < matchs.Count; i += 2)
            {

                int x = Convert.ToInt32(matchs[i].Value);
                int y = Convert.ToInt32(matchs[i + 1].Value);
                Point p = new Point(x, y);
                pointList.Add(p);
            }

            AddLine(geoLayer, pointList);
        }