ASP.NET

<WebMethod()> _
   Public Function Search(ByVal searchName As String) As System.Data.DataSet
       Dim connectionString As String = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString
       Dim con As New SqlConnection(connectionString)

       Dim selectSql As String = "SELECT * From Wine WHERE WineType='" & searchName + "'"

       Dim selectAdapter As New Data.SqlClient.SqlDataAdapter(selectSql, con)
       Dim ds As New Data.DataSet
       con.Open()
       selectAdapter.Fill(ds, "Wine")
       con.Close()

       Return ds

   End Function

Partial Class Search
    Inherits System.Web.UI.Page


    Dim searching As searchwine.Service = New searchwine.Service

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        If searchName.Text = "" Then
            lblDisplayError.Text = "Can't search empty field!"
        Else
            Dim ds As DataSet = searching.Search(searchName.Text)
            GridView1.DataSource = ds.Tables(0)
            GridView1.DataBind()
            GridView1.Visible = True
            lblDisplayError.Visible = False

        End If


    End Sub

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        lblDisplayError.Text = ""
        GridView1.Visible = False
    End Sub
End Class

System.NullReferenceException: Object reference not set to an instance of an object.
  at Service.Search(String searchName)