catch "double click" in datagrid column header cell

[bnathvbdotnet]

Dim pt As Point
Dim hti As DataGrid.HitTestInfo

pt = DataGrid1.PointToClient(Cursor.Position)
hti = DataGrid1.HitTest(pt)
If (hti.Type = DataGrid.HitTestType.ColumnHeader) Then
Messagebox.Show("double clicked")
End If

It says hti.type is 'none'

This code was available on syncfusion.com. I am not able to find out why it says none.