New Post: Very simple point in Polygon test not working

I tried to find the answer for hours, but I ended up with nothing.. this is a mystery to me.

The following code should do a simple point in Polygon test, but it always returns false for the intersection (I am definitely providing lat/lng coordinates that lies within the polygon):

      'load Shapefile
      Dim filedialog As OpenFileDialog = New OpenFileDialog()
        filedialog.Title = "Select shapefile (WGS1984 Projection)"
        filedialog.InitialDirectory = "C:\temp" 'DE_WGS1984.shp
        filedialog.RestoreDirectory = True
        If filedialog.ShowDialog() = DialogResult.OK Then
            TextBox4.Text = filedialog.FileName
        Else
            Exit Sub
        End If
        Dim ShapefilePoly As Shapefile = Shapefile.OpenFile(TextBox4.Text)
      
      'lngP/latP is the coordinate to test against the shapefile, e.g. 13.380025, 52.52972

                Dim PhotoPoint As New DotSpatial.Topology.Coordinate(lngP, latP)
                For Each f As DotSpatial.Data.Feature In ShapefilePoly.Features
                    Dim pg As DotSpatial.Topology.Polygon = TryCast(f.BasicGeometry, Polygon)
                    If pg IsNot Nothing Then
                        If pg.Contains(New DotSpatial.Topology.Point(PhotoPoint)) Then
                            LiesWithin = True 'never triggered
                            Exit Function
                        End If
                    End If
                Next

Could this be a rounding issue, because DotSpatial.Topology.Coordinate truncates lat/lng values beyond 6 decimals?
Thanks so much for any help..