private void CovertPolygonLayerToZones(PolygonZone zonDef, FeatureLayer polygLayer) 
{ 
int fcount = wpfMap1.TrackOverlay.TrackShapeLayer.InternalFeatures.Count; 
polygLayer.FeatureSource.Open(); 
IEnumerable allPolygons = polygLayer.FeatureSource 
.GetAllFeatures(ReturningColumnsType.AllColumns) 
.OfType (); 
MultipolygonShape mpolyg = new MultipolygonShape(allPolygons); 
Collection polyg= mpolyg.Polygons; 
for (int i=0;i<fcount,i++)
{
try 
{ 

Collection<Vertex> vtxs=polyg[0].OuterRing.Vertices; // this caused "Index was out of range" runtime problem 
} 
catch (Exception e) 
{ 
MessageBox.Show(ex.ToString(),"Exception"); 
} 
} 
}