Error using ExecuteIntersectionQuery method

Topics: General Topics
Nov 22, 2006 at 10:14 AM
Hi. I'm trying to use ExecuteIntersectionQuery method to do identify operations in VB.NET.
Here the code:

' ========== identify ====================
Dim l1 As SharpMap.Layers.VectorLayer = map.Layers(1)
Dim pt1 As SharpMap.Geometries.Point = New SharpMap.Geometries.Point(lon, lat)
Dim dts As New SharpMap.Data.FeatureDataSet
l1.DataSource.ExecuteIntersectionQuery(pt1, dts)
' ========================================

I get NullReferenceException while executing last code row where l1,pt1,dts are all successfully defined.
Anybody can help me to find what's wrong? (sorry for my english I'm italian).
Thanks

Giovanni