Another Issue With Sending Email From Feedback Form

Hello,
I have a Feedback form and have been looking for fixes all day and night and cannot figure out why its not working. It is not working on my local machine and I have no idea why, I get the following error
SendUsing" configuration value is invalid


using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Web.Mail;

/// <summary>
/// Summary description for Members
/// </summary>
public class Members
{
    public void SendEmail1(string strConfirm)
    {

        //The following code will send an email message:

  &nb ...