How to fix this error script ? Google maps

Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Try
            Dim mapquery As New StringBuilder
            Dim longitude As String = TextBox2.Text
            Dim Latitude As String = TextBox1.Text
            mapquery.Append("https://maps.google.com/maps/@")
            WebBrowser1.Navigate(mapquery.ToString())
            If TextBox1.Text <> String.Empty Then
                mapquery.Append(Latitude + ",")
            End If
            If TextBox2.Text <> String.Empty Then
                mapquery.Append(longitude + ",20z")
            End If
            WebBrowser1.Navigate(mapquery.ToString)
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub