How to place 20 mapicons

Question

after fetching 20 latlong from webservice,i tried to place 20 mapicons in my map.

I used for loop and placed the icons.

But only 2 or 3 map icons getting displays.

This is my code:

for (int i = 0; i < feed.data.Count(); i++)
{

if (feed.data[i].Longitude != "" && feed.data[i].Latitude != "")
{

var latlong = new Geopoint(new BasicGeoposition()
{ Latitude = Convert.ToDouble(feed.data[i].Latitude), Longitude = Convert.ToDouble(feed.data[i].Longitude) });
BasicGeoposition pos = new BasicGeoposition();
pos.Latitude = Convert.ToDouble(feed.data[i].Latitude);
pos.Longitude = Convert.ToDouble(feed.data[i].Longitude);
MapIcon MapIcon1 = new MapIcon();
MapIcon1.Location = new Geopoint(pos);
MapIcon1.NormalizedAnchorPoint = new Point(0.5,0.5);
MapIcon1.Visible = true;
// MapIcon1.ZIndex = int.MaxValue;
MapIcon1.Image = Windows.Storage.Streams.RandomAccessStreamReference.CreateFromUri(new Uri("ms-appx:///images/" + type + "map.png"));
ffMap.MapElements.Add(MapIcon1);

}
}